01 -
Heat cream in microwave until steaming. Add chopped chocolate, let sit 2 minutes, then whisk until smooth. Set aside to cool.
02 -
Preheat oven to 350°F. Grease a 9x13-inch cake pan with butter or baking spray.
03 -
Whisk cocoa powder with hot water or coffee until smooth and slightly thickened.
04 -
Whisk in brown sugar, sour cream, oil, eggs, and vanilla. Add flour, baking soda, baking powder, and salt, whisking just until combined.
05 -
Pour batter into prepared pan and bake 30-35 minutes until toothpick comes out clean. Cool completely, about 1 hour.
06 -
When ganache is room temperature and set to peanut butter consistency, beat until pale and fluffy, about 4 minutes. Spread on cooled cake.