For the Cake:
2 ounces bittersweet chocolate, finely chopped
3/4 cup hot coffee
1 1/2 cups (10 1/2 ounces) granulated sugar
3/4 cup buttermilk
1 large egg
1 egg yolk
7 tablespoons vegetable oil
1/2 teaspoon salt
1 1/2 teaspoons vanilla extract
1 1/4 cups (6 1/4 ounces) all-purpose flour
3/4 cup (2 1/4 ounces) cocoa
3/4 teaspoon baking soda
1/2 teaspoon baking powder

For the Peanut Butter Mousse:
8 ounces cream cheese
3/4 cup (3 ounces) confectioners' sugar
1 cup cream peanut butter
2 teaspoons vanilla extract
Pinch salt
1 cup heavy cream

For the Peanut Butter Ganache:
12 ounces bittersweet chocolate, finely chopped
1 cup plus 2 tablespoons heavy cream
2 tablespoons creamy peanut butter