These lemon poppy seed cupcakes with blackberry frosting are bright, zingy, and topped with the most gorgeous naturally purple buttercream — the kind of homemade lemon poppyseed cupcakes that make people ask for the recipe before they’ve even finished their first bite.
Okay, real talk — I made these on a whim one summer afternoon when I had a punnet of blackberries threatening to go soft on my counter, and honestly? Best impulsive baking decision I’ve ever made.
The lemon cupcakes are tender and citrusy, the frosting is fruity and creamy, and together they look like something straight out of a fancy bakery — except you made them in your kitchen in yoga pants. Let’s go.
Table of Contents
What Makes These Cupcakes So Good
These aren’t your average cupcakes. The sour cream in the batter keeps them impossibly moist, the fresh lemon zest and juice punch up the flavor without being overwhelming, and those little poppy seeds add just enough texture to make things interesting.
Then comes the frosting — real blackberries, cooked down into a thick, jewel-toned jam and folded into fluffy buttercream. No food coloring needed. Just pure, natural purple magic.
If you’ve been wondering how to make lemon poppyseed cupcakes that actually taste as good as they look, this is your answer. They’re approachable, impressive, and genuinely delicious. They’d be right at home alongside these honey peach cream cheese cupcakes at any summer gathering.
Lemon Poppy Seed Cupcakes with Blackberry Frosting
Equipment
- Muffin Pan (x2)
- cupcake liners
- stand mixer or hand mixer
- Large mixing bowls
- Sifter
- Blender or food processor
- Fine-Mesh Sieve
- Small saucepan
- Piping Bag with 1M Tip
- Wire cooling rack
- spatula
- toothpick
Ingredients
Lemon Poppy Seed Cupcakes
- 1 ½ cups all-purpose flour
- 1 teaspoon baking powder
- ½ teaspoon baking soda
- ¼ teaspoon salt
- ½ cup unsalted butter softened to room temperature
- 1 cup white sugar
- 2 tablespoons lemon zest about 2 lemons
- 2 large eggs
- 1 teaspoon vanilla extract room temperature
- ⅔ cup sour cream room temperature
- 3 tablespoons lemon juice freshly squeezed
- 1 ½ tablespoons poppy seeds
Blackberry Frosting
- 1 ½ cups blackberries fresh or frozen
- 1 cup unsalted butter softened to room temperature
- 4 cups powdered sugar
- ¼ teaspoon salt
- 1 tablespoon heavy cream if needed to adjust frosting consistency
Instructions
- Preheat the oven to 350°F and line two muffin pans with cupcake liners. This recipe makes about 14 cupcakes total.
- In a large bowl, sift together the flour, baking powder, baking soda, and salt. Give it a quick whisk to make sure everything is evenly combined.
- In a separate large bowl, beat the butter, sugar, and lemon zest together until light and fluffy. The zest rubbing into the sugar releases essential oils and seriously amplifies the lemon flavor.
- Beat in the eggs one at a time, followed by the vanilla extract. Scrape down the sides of the bowl as you go.
- With the mixer on low speed, beat in about half the sour cream followed by about half the flour mixture. Turn off the mixer and scrape down the sides of the bowl. Repeat with the remaining sour cream and flour mixture. Do not overmix once the flour is added.
- Gently fold in the fresh lemon juice and poppy seeds by hand using a spatula until just combined.
- Spoon the batter into the prepared liners, filling each about 2/3 full. Bake one tray at a time on the middle rack for 16–20 minutes, or until the tops look set and a toothpick inserted in the center comes out clean.
- Cool in the pan for at least 10 minutes, then transfer to a wire rack to cool completely before frosting.
- For the frosting: add the blackberries to a blender or food processor and blend until smooth. Press the puree through a fine mesh sieve to remove the seeds, working in batches and using the back of a metal spoon to push it through.
- Transfer the strained puree to a small saucepan over low heat. Bring to a gentle simmer, stirring occasionally, for 10–20 minutes until thick like jam. Remove from the heat and cool completely. You should have about 2–4 tablespoons of reduced puree.
- In a large bowl, beat the butter until soft and fluffy. Turn the mixer to low and beat in 2 cups of powdered sugar and the salt.
- Beat in 2 tablespoons of the thick, cooled blackberry puree. Then beat in the remaining powdered sugar about 1/2 cup at a time, adding a little more puree or cream as needed to reach your desired consistency.
- Transfer the frosting to a piping bag fitted with a 1M tip and frost the cooled cupcakes, or spread with a knife. Serve and enjoy!
Notes
Ingredients
For the Lemon Poppy Seed Cupcakes
| Ingredient | Amount |
|---|---|
| All-purpose flour | 1 1/2 cups |
| Baking powder | 1 teaspoon |
| Baking soda | 1/2 teaspoon |
| Salt | 1/4 teaspoon |
| Unsalted butter, softened | 1/2 cup |
| White sugar | 1 cup |
| Lemon zest (about 2 lemons) | 2 tablespoons |
| Large eggs | 2 |
| Vanilla extract, room temperature | 1 teaspoon |
| Sour cream, room temperature | 2/3 cup |
| Fresh lemon juice | 3 tablespoons |
| Poppy seeds | 1 1/2 tablespoons |
For the Blackberry Frosting
| Ingredient | Amount |
|---|---|
| Blackberries, fresh or frozen | 1 1/2 cups |
| Unsalted butter, softened | 1 cup |
| Powdered sugar | 4 cups |
| Salt | 1/4 teaspoon |
| Heavy cream (if needed) | 1 tablespoon |
Step-by-Step Instructions
Get Your Oven Ready
Preheat your oven to 350°F and line two muffin pans with cupcake liners. This recipe makes about 14 cupcakes total — which, yes, is a slightly awkward number, but just means you get two to test for “quality control.”
Mix the Dry Ingredients
In a large bowl, sift together the flour, baking powder, baking soda, and salt. Give it a quick whisk to make sure everything is evenly combined. This step only takes 30 seconds but it really does make a difference in the texture of your cupcakes.
Cream the Butter and Sugar
In a separate large bowl, beat the butter, sugar, and lemon zest together until the mixture is light, fluffy, and smells absolutely incredible — like a lemon cookie just walked into the room. That zest rubbing into the sugar releases all the essential oils and seriously amplifies the lemon flavor. Don’t skip the zesting!
Add the Eggs and Vanilla
Beat in the eggs one at a time, followed by the vanilla extract. The batter should look smooth and creamy at this point. Scrape down the sides of the bowl as you go — those little edges matter.
Alternate the Wet and Dry
With your mixer on low speed, add about half the sour cream, mix gently, then add half the flour mixture. Turn the mixer off, scrape down the sides, and repeat with the remaining sour cream and flour.
Alternating like this keeps the batter from getting tough — it’s one of those small steps that makes a big difference when you’re learning how to make lemon poppyseed cupcakes from scratch.
“Don’t overmix! Once the flour goes in, mix just until it disappears. Overmixing = dense, chewy cupcakes. We’re going for fluffy here.”
Fold in the Lemon Juice and Poppy Seeds
Gently fold in the fresh lemon juice and poppy seeds by hand using a spatula. The batter will look beautifully speckled and smell like lemon heaven. If you’ve ever made blueberry lemon poppy seed cupcakes or any lemon baked goods, you know that fresh juice at the end really brightens everything up.
Fill and Bake
Spoon the batter into the prepared liners, filling each about 2/3 full. Bake one tray at a time on the middle rack for 16–20 minutes, or until the tops look set and a toothpick inserted in the center comes out clean.
Let them cool in the pan for 10 minutes before moving them to a wire rack to cool completely. Do not frost warm cupcakes. I’m begging you.
Making the Blackberry Frosting
Reduce the Blackberry Puree
Add your blackberries to a blender or food processor and blend until smooth. Press the puree through a fine mesh sieve to remove the seeds — work in batches and use the back of a metal spoon to push it through. It takes a few minutes but it’s totally worth it for that silky, seed-free frosting.
Transfer the strained puree to a small saucepan over low heat. Simmer gently, stirring occasionally, for 10–20 minutes until it’s thick and jammy — like a concentrated blackberry sauce. You should end up with about 2–4 tablespoons of deep, intensely flavored puree.
Let it cool completely before adding it to the frosting. Room temperature. Promise me.
Build the Buttercream
Beat the softened butter in a large bowl until it’s super soft and fluffy. Turn the mixer to low and beat in 2 cups of powdered sugar and the salt. Add 2 tablespoons of the cooled blackberry puree and mix until combined — watch it turn the most gorgeous shade of purple!
Beat in the remaining powdered sugar about half a cup at a time. If it’s too thick, add a splash of cream. If you want a deeper berry flavor, add a bit more puree.
Transfer to a piping bag fitted with a 1M tip and frost those cupcakes like the baking superstar you are. Or just spread it on with a knife — honestly, it tastes just as good either way.
Expert Tips, Variations & Troubleshooting
Tips for the Best Lemon Poppy Seed Cupcakes
Room temperature ingredients are non-negotiable here — cold butter or eggs will mess with the emulsification and leave you with a lumpy batter. Pull everything out of the fridge at least 30 minutes before you start. For the most flavor, use unwaxed lemons and zest them before juicing — it’s so much easier that way.
If your frosting looks curdled or greasy, your butter was probably too warm. Pop the bowl in the fridge for 10–15 minutes and beat again — it’ll come right back together. Frosting troubleshooting is mostly just temperature management.
Fun Variations to Try
Want to try blueberry lemon poppy seed cupcakes? Swap the blackberries in the frosting for fresh blueberries using the exact same reduction method — you’ll get a beautiful blue-purple color and a slightly sweeter flavor. Raspberries work brilliantly too if you want something more tart and vibrant.
You can also fold a handful of fresh blueberries or blackberries directly into the cupcake batter for little bursts of fruit inside. It’s one of those small touches that makes homemade lemon poppyseed cupcakes feel extra special and bakery-worthy.
Storage Instructions
| Method | Duration |
|---|---|
| Room temperature (covered) | Up to 2 days |
| Refrigerator (airtight container) | Up to 5 days |
| Freezer — unfrosted cupcakes | Up to 2 months |
| Freezer — frosting (separate) | Up to 1 month |
Reheating tip: If your cupcakes have been in the fridge, let them come to room temperature for about 20–30 minutes before serving — cold butter-based frosting can taste a little dense straight from the fridge.
No-waste idea: Got leftover blackberry puree? Swirl it into yogurt, spoon it over pancakes, or stir it into lemonade for a gorgeous mocktail. Same goes for any extra frosting — it makes an incredible filling for sandwich cookies or a spread on toast (yes, really)
Nutritional Information (Per Cupcake, Approximate)
| Nutrient | Amount |
|---|---|
| Calories | ~380 kcal |
| Total Fat | 19g |
| Saturated Fat | 12g |
| Carbohydrates | 52g |
| Sugar | 40g |
| Protein | 3g |
| Fiber | 1g |
| Sodium | 145mg |
Values are approximate and will vary based on exact ingredients used.
Lemon Poppy Seed Cupcakes FAQs
Can I use frozen blackberries for the frosting?
Yes, absolutely! Frozen blackberries work perfectly for the puree since you’re cooking them down anyway. Just measure them while still frozen and add them straight to the blender — no need to thaw first. The flavor is just as rich and delicious.
Can I make these cupcakes ahead of time?
You can! Bake the cupcakes and make the frosting a day ahead, storing them separately. Keep the cupcakes covered at room temperature and the frosting in an airtight container in the fridge. Let the frosting soften at room temp for about 20 minutes and give it a quick beat before piping.
Why did my cupcakes sink in the middle?
This usually means they were underbaked or the oven door was opened too early. Make sure your oven is fully preheated before baking, and resist the urge to peek until at least the 15-minute mark. When in doubt, the toothpick test is your best friend.
Can I turn this into a lemon poppy seed layer cake instead?
Definitely! Double the recipe for two 8-inch round cake layers and bake at 350°F for about 28–32 minutes. The blackberry frosting is dreamy as a filling and outer frosting — it’d look absolutely stunning stacked up. Pair it with something savory afterward like this sourdough pesto grilled cheese for a truly excellent day.
Do I have to strain the blackberry puree?
You don’t have to, but you really should if you want a smooth, elegant frosting. Leaving the seeds in gives the buttercream a slightly gritty texture, which isn’t the most pleasant eating experience. The straining step takes about 5 minutes and makes a huge difference in the final result.
Go Make These!
Seriously, what are you waiting for? These lemon poppy seed cupcakes with blackberry frosting are the kind of recipe that looks wildly impressive but is genuinely doable on any regular weekend afternoon.
They’re bright, they’re beautiful, and they taste absolutely incredible. Whether you’re baking for a birthday, a brunch, or just because you deserve a really good cupcake — this one delivers every single time.
If you give them a try, I’d love to hear how they turned out! Drop a comment below with your experience, and if you made any fun variations, share those too. And if you’re feeling generous (and you should be, because these are that good), save this recipe to your Pinterest boards so your friends can find it too — they’ll thank you for it.
