Chocolate And Butterscotch Mousse Cake

¾ cup all-purpose flour ⅓ cup unsweetened cocoa powder 1 teaspoon baking powder ½ teaspoon baking soda ½ teaspoon ground cinnamon ¼ teaspoon salt ⅓ cup unsalted butter, softened ¾ cup sugar 2 eggs 1 teaspoon vanilla ½ cup sour cream 1 recipe Chocolate Frosting (optional) Chocolate sprinkles (optional)

Chocolate Mousse

1 ½ cup whipping cream 8 ounce bittersweet chocolate, finely chopped (about 3/4 cups)

Butterscotch Mousse

1 ½ cup whipping cream 8 ounce butterscotch chips

Chocolate Frosting

¼ cup butter or margarine 3 tablespoon unsweetened cocoa powder 3 tablespoon buttermilk 2 ¼ cup sifted powdered sugar ½ teaspoon vanilla ½ cup chopped walnuts