This recipe has been on my mind since last summer’s Lemon Blueberry Cake. That was a lemon cake included with blueberries in the batter. My in-laws loved the cake, which surprised me, and my wife told me after the fact that one of the more popular Cheesecake Factory flavors growing up was lemon raspberry. Hence, the idea for this cake.

This is the same lemon cake from that recipe. However, I wanted to remove the berries and replace them with a raspberry curd in between layers. Since the raspberry curd used egg yolks, I thought it would be the perfect time to try Swiss meringue buttercream, which uses egg whites (no wasted eggs!). I waffled in the grocery store, though, deciding to double the recipes with which I had planned. This resulted in a ton of curd and a ton of frosting. This led me to other decisions, some good and some bad (in hindsight).

I didn’t want the curd, which was more liquid than the lime curd I previously made, to saturate the cake layers. So, I decided to spread icing on the top of a layer, pour some curd on top, then spread icing on the bottom of the next layer with the intention of “sealing” in the curd between layers of frosting. Obviously, this did not work, and most of the curd (>90%) flowed out of the cake, onto the table, and into the panicked outer layer of frosting. I let the frosting set in the fridge for a little while before continuing and while I cleaned up my mess. In hindsight, I think the raspberry curd would have been fine between the layers… without frosting. The travesty here was that the curd might have been the best part of the cake. When I ate it, I just poured it on top of my slice(s).

For Easter, I wanted to the decorations to be more festive, so I added some food coloring and tried my hand at some new piping (ribbons! but also since I had so much frosting). This worked well to cover up the curdisaster, and the cake ended up looking pretty good.

The SMB was different than my normal frostings, much more pillowy. Sadly, I was worried about the structural integrity of the cake, so I left it in the fridge to chill overnight, and the frosting hardened wayyyy too much. This didn’t make the cake very enjoyable the first night, but I left it out on the counter to try the next night, and it was better. Ultimately, I wasn’t very pleased with my performance here. Good idea, bad execution.

In the future, I would probably halve the recipes below for both the curd and the frosting. Unless you’re decorating, 1 1/2 cups curd and 5 cups of frosting will be plenty. I also think I would try the swiss meringue buttercream at Cake Paper Party because it is a recipe that works using pasteurized egg whites from a carton (less of a waste if I’m not making curd). I would also entertain, at least for this cake, a lemon-raspberry curd (like this one), because it might be thicker than what I made here.

LEMON RASPBERRY CAKE
Based on recipes found here, here, and here.

INGREDIENTS

Lemon Cake:
1 cup unsalted butter, softened to room temperature
1 1/4 cups (250 g) granulated sugar
1/2 cup (100 g) light brown sugar
4 eggs, room temperature
1 tbsp. vanilla bean paste
3 cups (360 g) all-purpose flour, sifted
1 tbsp. baking powder
1/2 tsp. salt
1 cup buttermilk
zest + juice of 3 medium-sized lemons

Raspberry Curd:
16 tbsp. unsalted butter
24 oz. raspberries (or 1 pint)
10 large egg yolks (reserve egg whites for the frosting)
1 1/2 cups (300 g) granulated sugar
1/4 tsp. salt
4-6 tsp. fresh lemon juice, to taste

Vanilla Bean Swiss Meringue Buttercream:
10 large egg whites
2 1/2 cups (500 g) granulated sugar
3 cups unsalted butter, cut into cubes and cool (not chilled)
3 tbsp. + 1 tsp. vanilla bean paste
Pinch of kosher salt

DIRECTIONS:

1. For the curd: Place 1-2 inches of water in bottom of a double boiler and bring to a boil over high heat. Reduce heat to low in order to maintain a simmer.
2. Melt butter in top of double boiler. Add raspberries, egg yolks, sugar, and salt. Cook, mashing the berries and whisking constantly until thickened (~10 minutes).
3. Pour mixture through a coarse strainer set over a bowl, and extract as much liquid as possible. Cool to room temperature. Stir in lemon juice to taste.
4. Cover curd with plastic wrap and refrigerate overnight.
5. For the cake: Preheat oven to 350 degrees. Butter and flour three 8″ cake pans.
6. In a medium bowl, whisk together the flour, baking powder, and salt, then set aside.
7. In small bowls or cups, prepare lemon zest and juice, then set aside.
8. Cream butter in a stand mixer on high speed for 2 minutes, then add sugar and continue mixing a few more minutes on medium-high speed.
9. Add eggs and vanilla mixing on medium speed for a minute or two until combined.
10. Add the dry ingredients and mix briefly (~5 seconds).
11. Remove bowl from stand mixer and fold in buttermilk, lemon zest, and lemon juice until combined.
12. Pour batter into cake pans (~530 g per cake). Bake for 25-30 minutes or until toothpick inserted into the center comes out clean (it took 25 minutes in my oven). Allow cakes to cool for 10 minutes, then flip onto wire rack to cool completely.
13. For the frosting: Place 1-2 inches of water in bottom of a double boiler and bring to a boil over high heat. Reduce heat to low in order to maintain a simmer.
14. In top of double boiler, add sugar to egg whites, then place over simmering water. Gently whisk until sugar is dissolved and the mixture is hot (~12 minutes to 140 degrees).
15. Transfer mixture to the bowl of a stand mixer fitted with the whisk attachment. Beat on medium-high speed until egg whites are smooth and glossy and the bowl is neutral to touch (~10-20 minutes… may have to stop the mixer to allow for faster cooling).
16. Switch to paddle attachment and set speed to the lowest possible setting. Add butter, one cube at a time, and continue mixing until the butter is completely incorporated, there are no lumps, and the frosting is smooth and silky (keep mixing if frosting appears to be curdled).
17. Add the vanilla bean paste and food coloring, mixing on low until just incorporated.
18. For the assembly: Spread a thin layer of frosting on bottom layer of cake, then add half of the curd.
19. Top with middle layer of cake, spread a thin layer of frosting followed by the remaining curd.
20. Add final layer of cake, then frost as desired.