- 3/4 cup boiling water
- 1/2 cup unsweetened cocoa powder (not Dutch-process)
- 1 teaspoon instant-espresso powder
- 1/2 cup whole milk
- 1 teaspoon vanilla
- 2 cups all-purpose flour
- 1 teaspoon baking powder
- 1/4 teaspoon salt
- 1/2 cup unsalted butter
- 1/2 vegetable oil
- 2 cups packed dark brown sugar
- 2 large eggs
- 2 egg yolks
Ganache filling and glaze
- 2 1/2 cups heavy cream
- 15 ounces finely chopped, dark chocolate
- 1/2 cup semi sweet chocolate chips
- 1/4 – 1/2 cup granulated sugar
Make ganache before baking cake:
- Bring cream to a simmer in a 3- to 4-quart saucepan and remove from heat.
- Whisk in all chocolate until smooth. Add sugar. Stir well.
- Transfer ganache to a bowl and chill covered, stirring occasionally, until thickened but spreadable, about 3 hours. If ganache becomes to thick, let stand at room tempature until slightly softened.
For cake layers:
- Preheat oven to 350°F.
- Butter and dust 2 round cake pans (7 or 8 inch) with flour, knocking out excess.
- Whisk together water, cocoa, and espresso powder until smooth, then whisk in milk and vanilla.
- Sift together flour, baking soda, and salt.
- Beat together butter, oil and brown sugar in a large bowl with an electric mixer at high speed until fluffy, then add eggs 1 at a time, beating well after each addition.
- Add flour mixture and cocoa mixture in batches, beginning and ending with flour and mixing at low speed until just combined.
- Divide batter among pans, smoothing tops. Bake in middle of oven until a tester comes out clean, 30 to 35 minutes for 7-inch pans or 20 to 25 minutes for 8-inch. Cool in pans on a rack 30 minutes, then invert onto racks and cool completely.
- Arrange 1 layer on a cake stand or plate and spread ganache evenly over it.
- Top with other cake layer and 2/3 cup ganache, spreading evenly.
- Chill cake until ganache filling is firm, about 1 hour.
- Spread remaining ganache evenly over top and sides of cake.
- Chill ganache if necessary to keep at a spreadable consistency.