for the cake
4 large eggs (room temperature)
2 egg yolks (room temperature)
1 tablespoon pure vanilla extract
1 1/4 cups (296 mL) buttermilk, divided
3 cups (285 grams) cake flour
2 cups (450 grams) granulated sugar
4 1/2 teaspoons aluminum-free baking powder
1/2 teaspoon fine salt
1 cup (227 grams) unsalted butter (room temperature)
Preheat oven to 350F/177C. (For kitty cake, grease two 9x2 inch round pans then line with parchment rounds. Line a muffin pan with cupcake papers for remaining batter.) For triple layer cake, grease three 8 or 9-by 2 inch round baking pans, then line with parchment rounds. Grease the parchment.
Whisk eggs and yolks in medium bowl. Add vanilla and 1/4 cup (59 mL) buttermilk, whisk. If desired, transfer to large liquid measuring cup for easier pouring.
In large mixing bowl, combine flour, sugar, baking powder, and salt. Whisk to blend. Add butter and remaining buttermilk. Turn mixer on lowest speed and pulse (turn on and off quickly) to mix the dry ingredients in. Increase speed to medium until fluffy, 2 minutes.
Add the eggs in 3 additions, scraping down bowl each time, and mix only until incorporated. Divide the batter among the pans. A kitchen scale helps ensure the batter is evenly divided.
Bake layers until a tester comes out clean and the cake begins to pull away from the pan, about 22 minutes for 9 inch layers, 30 minutes for 8 inch layers, 24 minutes for cupcakes. As oven temperatures vary, keep an eye on the cakes and don't touch the pans until the top is set, else you risk the cakes deflating.
Cool in pans for 10 minutes, then turn layers out onto wire racks to cool completely. If not frosting immediately, wrap each layer tightly in plastic wrap and freeze. Defrost in fridge. Cupcakes can be frozen in a well-sealed container.
To assemble layer cake, place first layer flat-side-up on serving plate or cake stand. Spread 3/4 cup frosting to the edge of cake, repeating with the next layer. Top with the third layer and use all but 3/4 cup frosting to cover the top and sides. Place reserved frosting in pastry bag fitted with star tip and pipe a border around base of cake and top layer.
(To assemble kitty cake, please refer to the Kitty Cake post.)
Instant Fudge Frosting
6 ounces 85% cacao chocolate, melted and cooled (I used Lindt)*
4 1/2 cups confectioners' sugar
1 1/2 cups unsalted butter (room temperature)
6 tablespoons half and half
1 tablespoon vanilla extract
1 teaspoon brewed coffee (breakfast leftovers are fine)
*if making the Kitty Cake, you may wish to further darken the frosting with a black gel food coloring
equipment: large food processor**, double boiler
Fill bottom of double boiler (I use a small saucepan and a heat-proof glass bowl for my double boiler) with about 1/2 inch (1 cm) of water. Chop chocolate into small pieces and place in top of double boiler. Heat water over medium heat to a boil, then reduce heat and simmer. Stir chocolate frequently until melted, remove from heat. Cool to room temperature, about 72F/22C.
Fit food processor bowl with S blade. Add confectioners' sugar, butter, half and half, and vanilla. Pulse to combine, then drizzle in cooled chocolate and process until well blended. If not using immediately, transfer to bowl, press plastic wrap directly on surface of frosting, and cover bowl with lid. Refrigerate until ready to use, then bring to room temperature and mix briefly on low speed with electric mixer before icing the cake.
**If you don't have a food processor, beat the butter and sifted confectioners' sugar in stand mixer fitted with paddle attachment on low for 1 minute, then increase speed to medium-high for 1 minute. Add half and half, vanilla, and cooled chocolate, then beat on low to combine, then medium-high for 2 minutes.
adapted from Sky High via Sweetapolita