Chocolate peanut butter cake

Makes two 9-inch (23cm) layers. Rounded quantities below are for the whole cake.

Adapted from Preppy Kitchen’s recipe. Flat-layer guide.

All amounts are by weight, including liquids. Baker’s percentages use the cake’s 280g flour as 100% throughout, including frosting and ganache; they are not shares of the total mixture. For example, 50% means 140g.

Cake

• 280g [100%] all-purpose flour
• 460g [164.3%] sugar
• 85g [30.4%] unsweetened cocoa
• 200g [71.4%] buttermilk
• 130g [46.4%] beaten egg (beat 3 large eggs; weigh without shells)
• 140g [50%] vegetable oil
• 10g [3.6%] vanilla
• 8g [2.9%] baking soda
• 5g [1.8%] baking powder
• 4g [1.4%] fine salt
• 200g [71.4%] hot coffee or water

Frosting

• 290g [103.6%] softened unsalted butter
• 275g [98.2%] creamy, no-stir peanut butter
• 500g [178.6%] powdered sugar
• 10g [3.6%] vanilla
• 1g [0.4%] fine salt
• 50–60g [17.9–21.4%] milk

Ganache

• 145g [51.8%] chopped dark chocolate
• 100g [35.7%] heavy cream

Method

1. Grease two 9-inch round cake pans, at least 2 inches deep; line bottoms with parchment. Heat oven to 350°F (175°C). Fill no more than ⅔ full; bake any extra batter separately.
2. For flatter layers, soak fabric cake strips 5–10 minutes, squeeze, and fit around pans.
3. Whisk dry cake ingredients. Combine buttermilk, eggs, oil, vanilla; stir into dry mixture, then add hot coffee or water.
4. Divide evenly. Start checking at 30 minutes; bake until centers spring back and a tester has no wet batter. Timing may vary with your pan and cake strips. Cool 15 minutes; unmold and cool completely.
5. Beat butter and peanut butter; add vanilla, salt, then gradually sugar and 50g milk. Whip fluffy; add up to 10g more milk if needed.
6. Fill, stack, frost; chill 20 minutes.
7. Pour steaming cream over chocolate; wait 5 minutes, stir. Cool until barely warm; spread atop cake. Chill 30 minutes.

Only one pan? Make two separate half-batches of the cake batter, mixing the second just before baking. Cool, clean, and re-line the pan between layers. Use half of every cake ingredient per batch, including 65g beaten egg. Make the frosting and ganache once using the full amounts above.