This Poppy Seed Lemon Cake features three layers of lemon cake with poppy seed cream cheese filling and brown sugar Swiss buttercream frosting.
When building your cake recipe collection, you need to master three staple cake flavors: vanilla, chocolate, and lemon. Once you’ve got those down, you’ll be equipped to make hundreds of different variations.
This recipe is a variation of my go-to lemon cake. It’s the same cake base used to make this lemon layer cake with mascarpone buttercream.
Lemon Poppy Seed Cake with Brown Sugar Buttercream
This isn’t your standard lemon poppy seed cake. It’s a lemon cake with a poppy seed buttercream filling.
Instead of folding the poppy seeds into the cake batter, the seeds are incorporated into a filling. Rather than getting lost in the cake batter, the poppy seeds have a purpose.
Why add poppy seeds?
The poppy seeds add a crunchy texture, while also providing a little bit of nutty flavor.
Poppy seeds also adds a bit of nutrients. They supply a decent amount of calcium, iron, and magnesium.
Check out the nutritional facts of a bag of poppy seeds. A three tablespoon serving of poppy seeds contains 11 grams of fat. Poppy seeds are rich in fats that help to lower LDL (“bad cholesterol”) while helping to increase HLD (“good cholesterol”) in the blood.
Still not a fan of poppy seeds? Simply omit them. The cream cheese filling will still be just as tasty.
Poppy Seed Cream Cheese Filling:
The poppy seed cream cheese filling combines softened butter and cream cheese until smooth. The mixture is flavored with three variations of lemon: lemon zest, lemon juice, and lemon extract.
A small amount of vanilla extract is added to round out the tart notes of lemon. The poppy seeds are mixed in at the end once the filling is thick and smooth.
But the thing that really makes this lemon cake stand out is the brown sugar Swiss buttercream that frosts the outside of the cake.
Brown Sugar Swiss Meringue Buttercream:
Traditionally, Swiss meringue buttercream is made with granulated sugar. This version uses dark brown sugar.
Brown sugar is simply granulated sugar that is re-mixed with molasses.
What’s the difference between light brown versus dark brown sugar?
The amount of molasses added to the sugar! Dark brown sugar is darker in color because there is more molasses.
There is a subtle difference in taste and moisture content. However, for this recipe, you can use dark or light brown interchangeably.
This poppy seed lemon cake is not too sweet. It’s the kind of cake you can definitely enjoy for breakfast.
Do not be overwhelmed by the components needed for this assembled cake. The lemon cake can be baked ahead of time. It stays moist several days after baking.
For even longer storage, the lemon cake layers can be frozen up to a month. Simply allow cake to defrost at room temperature before use.
Interested in more lemon recipes? Here are some favorites:
- Lemon Cake with Mascarpone Buttercream
- Spring Thyme Lemonade
- Meyer Lemon Ricotta Pancakes
- Lemon Rosemary Cake
Poppy Seed Lemon Cake
Ingredients
Lemon Cake:
- 2 ¼ cup all-purpose flour
- 1 teaspoon baking powder
- 1 teaspoon baking soda
- ½ teaspoon kosher salt
- ¾ cup unsalted butter, softened
- 1 ¼ cup granulated sugar
- 1 Tablespoon finely grated lemon zest
- 3 large eggs, room temp
- ⅓ cup sour cream, room temp
- ⅔ cup whole milk, room temp
- 5 Tablespoon fresh squeezed lemon juice
Poppy Seed Cream Cheese Frosting:
- ½ cup unsalted butter, softened
- 4 oz cream cheese, softened
- 3 ½ cups confectioners' sugar
- 1 teaspoon finely grated lemon zest
- 1 Tablespoon fresh squeezed lemon juice
- 1 teaspoon high quality lemon extract
- ¼ teaspoon high quality pure vanilla extract
- 4 Tablespoon poppy seeds
Brown Sugar Swiss Meringue Buttercream:
- ½ cup egg whites
- 1 ¼ cup dark brown sugar, packed
- 2 cups unsalted butter,
- ½ teaspoon kosher salt
Instructions
Lemon Cake:
- Preheat oven to 350°F. Line three 6-inch cake round pans with parchment paper. Lightly grease and set aside.
- In a large bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
- In the bowl of a stand mixer fitted with a paddle attachment, cream butter. Add sugar and lemon zest. Beat until smooth. Add eggs and continue to mix on medium speed until incorporated. Add sour cream and mix. Scrape down bowl as needed to ensure thorough mixing.
- Add flour mixture in three additions, alternating with milk. Begin and finish with flour mixture. Add lemon juice and mix until well incorporated.
- Divide batter evenly among the three prepared cake pans. Level batter using a mini offset spatula, or the back of spoon. Bake for 35-38 minutes until a toothpick inserted in center of cake comes out clean. Let cake cool in pan for 5 minutes, then run a mini offset spatula around the cake and unmold. Let cake cool to room temperature on wire rack.
Poppy Seed Cream Cheese Filling:
- In the bowl of a stand mixer fitted with a paddle attachment (or using a handheld electric mixer), beat butter and cream cheese until smooth. Add confectioners' sugar, lemon zest, lemon juice, lemon extract, and vanilla extract. Beat until smooth. Scrape down as needed to ensure thorough mixing. Add poppy seed and mix on low speed until distributed. Set aside.
Brown Sugar Swiss Meringue Buttercream:
- In the bowl of a stand mixer, whisk together egg whites and brown sugar. Place bowl over a pot of simmering water to create a bain-marie or double boiler. Make sure the simmering water does not touch the bottom of the bowl. Whisk sugar-egg mixture until it reaches a temperature of 160°F.*Alternatively, if you don't have a thermometer, heat the mixture until all the sugar has melted. Test this by dipping your pointer finger into the mixture and rubbing it against your thumb. The mixture should be smooth. You should not be able to feel the granules of sugar.
- Return bowl to the stand mixer. Using the whisk attachment, beat mixture at medium speed until it has cooled to room temperature. Reduce speed to low and add butter one tablespoon at a time.
- Once all the butter has been incorporated, add salt. Increase speed to medium-high and continue to beat until buttercream is light and fluffy.
Assembly:
- Level cake layers are necessary. Place one cake layer on serving platter or cake turntable. Spread ½ cup poppy seed cream cheese frosting on cake. Place second cake layer and repeat with another ½ cup of poppy seed cream cheese. Add third cake and spread ⅓ cup of poppy seed cream cheese.
- Spread a thin layer of poppy seed cream cheese frosting around the sides of the cake to seal in the crumbs (crumb coat). Place cake in the fridge and allow to chill for 15-20 minutes to set the buttercream.
- Spread an even layer of brown sugar Swiss buttercream all over the cake. Chill cake in the fridge for another 15 minutes to set buttercream.
- Meanwhile, fit a decorating bag (piping bag) with a medium star tip. Fill bag with about ½ cup of brown sugar Swiss buttercream. Pipe rosettes along the surface border of cake. Sprinkle poppy seeds over rosettes. If desired, decorate rosettes with small slices of lemon. Return cake to fridge until ready to serve.
- Let chilled cake sit at room temperature for 15 minutes before serving to allow cake to soften.
Notes
- Lemon cake can be baked ahead of time (up to 2 days before assembly). Allow to cool to room temperature before wrapping in plastic wrap. Cake can also be stored in the freezer for up to a month. Simply allow cake to defrost at room temperature before use.
- Cake batter can also be baked as three 8-inch round cakes. Bake for 30-35 minutes until toothpick inserted in center of cake comes out clean.
