- 2 9-inch round cake pans
- 2 1/4 cups all-purpose flour
- 2 teaspoons baking powder
- 1/2 teaspoon salt
- 1 1/4 cup whole milk, room temperature
- 4 large egg whites, room temperature
- 12 tablespoons unsalted butter, softened
- 1 1/2 cups sugar
- 2 teaspoons vanilla extract
- zest from 1 lemon
- 4 large egg whites
- 1/4 teaspoon salt
- 1 1/4 cup sugar
- 12 ounces unsalted butter, very soft
- Juice of 1 lemon
- 2 - 3 tablespoons blackberry jam, for cake layers
- 7 - 8 blackberries, for decorating
Prep: 20 minutes Bake: 35 - 45 minutes
Preheat oven to 325. Butter the sides of the two cake pans and line the bottom with parchment paper.
In a medium bowl, whisk together flour, baking powder, salt, and lemon zest. In a small bowl, whisk together milk and egg whites. Set both bowls aside.
In a large bowl, combine the butter and sugar and beat with an electric mixer on low speed until well combined. Increase speed to medium-high and mix until creamy and pale, about 8 - 10 minutes, scraping down the bowl as you go. (I used to be afraid of overmixing at this part because it can take a good minute to achieve the almost-white color and the fluffiness you need. But don't worry about overmixing in a plain butter and sugar mixture.) Beat in vanilla extract.
You'll now begin to add the liquid and flour mixtures into the creamed butter in stages. On low speed, begin by adding about a fourth of the flour mixture and mix until just combined. Increase speed to medium and add a third of the milk-egg mixture. It may be difficult to mix the liquid into your fatty mixture, but it will happen and it will get easier at each additional addition. Continue to add flour and milk mixtures in stages, beating the mixture until combined after each addition of flour or liquid. Before adding the last fourth of flour, give the bowl a good scrape with a rubber spatula. Combine flour and proceed to beat mixture on medium for 4 - 6 minutes.
Pour batter in equal amounts into prepared cake pans and place on the middle rack of the preheated oven. Bake 35 - 45 minutes. I advise beginning to check the cakes after 25 minutes in the oven.
Note: The baking temperature for a cake is usually 350. Baking at a lower temperature for a longer period of time helps keep the cake moist and prevents the cake from doming up in the middle. You can also invest in cake strips, which are fabric or silicon strips that wrap around the cake pan and help it bake evenly. Or you can bake at 350 for a shorter period of time without the strips and if the cake does dome, just use a knife to cut the offending portions off. There's nothing wrong exactly with a domed cake save for ease of layering and aesthetics.
When cake is baked, remove from oven and let cool in pan for 5 - 10 minutes. If the sides of the cake haven't pulled away from the cake pan, use a small paring knife and run along the edges of the pan, pressing against the pan and not the cake, to loosen the cake from the pan. Once cool, place cake on a wire rack to complete cooling. I prefer to bake my cakes a day in advance, wrap in cling form once they are cool, and refrigerate overnight. This helps with the crumb texture of the cake and also ensures that the cakes are nice and cool before the buttercream is added. Buttercream added to a warm cake = melted buttercream + sad cake-eaters.
Prep: 25 - 30 minutes
If you're nervous about the egg whites, don't be. The first step for this recipe is to bring a medium pot of water to a rolling boil, lower temperature to a gentle boil; place a heat resistance bowl over top of this pot; add the sugar, salt, and egg whites; and whisk CONSTANTLY until the sugar has totally dissolved. This will take about 5 minutes and will effectively cook the egg whites. Important in this step: make sure the boiling water does not reach the bowl with your ingredients. The water should boil just under the bowl. You don't want to risk making scrambled egg whites by overheating too quickly. Great Tip: If you aren't sure if the sugar id dissolved, drop a bit of the mixture on your finger. If it still feels grainy, continue to whisk over the boiling water. If it doesn't, your good to move to the next step. Essential Tip: Do not leave the egg white mixture alone. Whisk constantly throughout this process or the egg whites will scramble.
Remove bowl from the stove and beat on medium-high speed until the meringue is about double in volume and beginning to cool. The bowl should be just slightly warm to the touch, including on the bottom where the bowl was once over the boiling water. This should take somewhere between 4 - 6 minutes. Once the meringue has doubled in size, lower the mixer to low-medium or low and continue to beat until the bowl is completely cooled. This helps with two things. One: When the bowl has cooled, you know you have beaten your meringue long enough to produce a thick buttercream. Two: The bowl must be cool before you add the softened butter or the butter will melt, ruining all the time you've put into this recipe.
Once the bowl is cool, continue to mix on low speed. Add small squares of butter in 6 - 8 additions, mixing thoroughly after each addition of butter. Once all the butter has been added, increase mixer speed to medium and beat for 8 - 10 minutes until the buttercream is smooth, thick, and shiny. The butter should be fully incorporated and there should be a nice clean sheen to the buttercream. Great tip: It is perfectly normal, even likely, that the icing will separate during the process of adding butter or shortly after. The buttercream will look curdled and ruined if this happens. But it isn't! Keep mixing through it and it will come together.
After the buttercream is smooth and shiny, add the juice of lemon one tablespoon at a time, mixing after each addition. This will prevent the buttercream from separating or from becoming too thin. Taste after each addition to make sure the buttercream isn't too tart. Great tip: It is, again, perfectly normal, even likely, that when the lemon juice is added the buttercream will separate. If this happens, beat on medium speed for at least 5 minutes.
Use buttercream to frost your butter cake!
To produce this Blackberry Butter Cake, I put one thin layer of buttercream on my first layer. I then piped a circle around the outside of the cake and filled the inside of that circle with blackberry jam. I piped another circle around the jam, about half an inch higher than where the jam ended, and encased the jam with more buttercream. I wanted a nice thick layer of buttercream and jam between my two cake layers for the dramatic look and because I didn't plan on icing the outside of my cake. I stacked the second cake on the buttercream, added more buttercream, and used an angled spatula to get a nice smooth finish on top (there isn't nearly as much buttercream on the top as in the middle). I used a small star piping tip to make a border along the outside of the cake. I then halved 7 blackberries and made a circle of blackberries just inside the piped border.
Alternatively, if you would like to ice the outside of your cake, you could do one thin layer of buttercream. Like this: bottom cake layer, buttercream, blackberry jam, top cake layer. You would then have quite a bit of buttercream left to ice the entire cake.