This lemon poppy seed raspberry cake is made with a light and zesty lemon cake freckled with poppy seeds. The moist cake is layered with sweet raspberry jam and creamy, luxurious French buttercream.
Why we Love Lemon Poppy Seed Cake
The lemon poppy seed cake is soft and fluffy. I like the added texture of the poppy seeds. Using both cake flour and buttermilk keep the layer tender. Cake flour has less protein than all-purpose flour while the acidity in the buttermilk imparts tang and tenderness.
For extra lemon flavor, I bet a lemon simple syrup to soak the cake layers would be nice. Instead, I opted for tart yet sweet seedless raspberry jam for an extra punch of flavor and color.
Creamy French Buttercream
Where both Italian and Swiss meringue buttercream use egg whites, French buttercream is made with egg yolks. As you can imagine, the egg yolks make this buttercream rich and almost custard-like.
While French buttercream isn't usually my go-to frosting, it is luscious and creamy. I occasionally make French buttercream when I want something a bit richer or warmer. I have a recipe in my cookbook that pairs molasses French buttercream with pumpkin cake that is truly divine.
Once whipped, French buttercream is as silky as other meringue-based buttercreams. It glides effortlessly over cakes and has a melt-in-your-mouth quality.
Tips for Making French Buttercream
- Unlike with Italian meringue buttercream, make sure the mixer is on LOW speed when adding the hot sugar syrup to the egg yolks.
- Make sure that the butter is softened but not greasy or melted.
- Once the butter is incorporated, turn the mixer up to medium-high and beat for about 1 minute until smooth and silky. Reduce the speed to low and mix for another minute to knock out any air bubbles.
- If it's soupy or thin, the butter was likely too warm. Chill everything is the refrigerator for 5 to 10 minutes then mix again.
- If it's curdled or greasy, the butter was likely too cold. Keeping mixing until the butter emulsifies.
New to making layer cakes? Be sure to review How to Ice a Cake.
Lemon Poppy Seed Cake with Raspberry Jam
For the Lemon Poppy Seed Cake
- 3 cups + 2 tbls cake flour
- 2 ½ teas baking powder
- ½ tea baking soda
- ½ tea salt
- 4 teas poppy seeds
- 1 cup unsalted butter, softened
- 1 lemon, zested
- 2 cups granulated sugar
- 1 tea vanilla
- 4 eggs
- 1 cup buttermilk
- ¼ cup lemon juice
For the French Buttercream
- 2 cups granulated sugar
- 1 cup water
- 2 tablespoon corn syrup
- pinch cream of tartar
- 5 egg yolks
- 1 whole egg
- 3 cups unsalted butter, softened and cut into thin pieces
- 1 tablespoon pure vanilla extract
- ⅔ cup raspberry jam
To Make the Lemon Poppy Seed Cake
- Pre-heat the oven to 350°F (175°C). Grease, flour, and the line the bottoms of three 8-inch (20-cm) cake pans with parchment paper and set aside.
- Sift together the flour, baking powder, baking soda, and salt. Stir in the poppy seeds and set aside.
- In the bowl of a stand mixer fitted with the paddle attachment, beat the butter on medium speed for 2 minutes. Meanwhile, rub the sugar and lemon zest together in a small bowl between your fingertips until fragrant. Add the sugar mixture and mix on medium-high until light and fluffy, 3 to 5 minutes. Stop the mixer and scrape down the bowl.
- Turn the mixer to medium-low and add the vanilla and eggs, one at a time. Mix until combined. Stop the mixer and scrape down the bowl.
- Combine the buttermilk and lemon juice together in a liquid measuring cup or bowl. Turn the mixer to low and add the flour mixture in three batches, alternating with the buttermilk mixture, beginning and ending with the flour mixture. Mix on medium for no more than 30 seconds after the last streaks of the flour mixture are combined.
- Evenly distribute the batter between the prepared pans. Bake for 26 to 28 minutes or until a toothpick inserted into the center of the cakes comes out clean. Let them cool on a wire rack for 10 to 20 minutes before removing the cakes from their pans. Once cool, remove the parchment paper and discard.
To Make the French Buttercream
- Place the sugar, water, corn syrup, and cream of tartar in a medium-small saucepan. Gently stir to combine. Heat the sugar mixture, without stirring, until it reaches 235F on a candy thermometer.
- Meanwhile, place the egg yolks and whole egg in the bowl of a stand mixer. Using the whisk attachment, whip the eggs on high until thick and pale in color.
- Once the sugar mixture reaches the correct temperature, remove it from the heat. Turn the mixer down to LOW speed, and slowly pour the hot sugar mixture into the eggs. Once all of the sugar mixture has been added, increase the mixer speed back up to medium-high and continue to whip until the outside of the mixer bowl returns to room temperature, about 8 minutes.
- Once the mixture has cooled, stop the mixer and swap the whisk attachment for the paddle. With the mixer on medium-low, add in the bits of butter, a little at a time. Add the vanilla. Once incorporated, turn the mixer up to medium-high and beat for about 1 minute until smooth and silky. Tint the buttercream with gel food cooling, if desired.
To Assemble the Cake
- Place one layer of cake on a cake stand or serving plate. Spread on about ½ cup of buttercream with an offset spatula. Dollop on about ⅓ cup of raspberry jam and smooth. Top with the middle layer of cake and repeat. Place the last layer of cake on top, bottom-side up. Crumb coat the cake with the buttercream and chill in the refrigerator for about 15 minutes.
- Removed the chilled cake and frost with the remaining buttercream. Decorate with fresh flowers or as desired.