Cake:
Nonstick vegetable oil spray
3 cups all purpose flour
2 cups sugar
2/3 cup sifted natural unsweetened cocoa powder (sifted, then measured)
2 teaspoons baking soda
1 teaspoon salt
2 cups water
2/3 cup vegetable oil
2 tablespoons apple cider vinegar
2 teaspoons vanilla extract

FILLING:
8oz semi-sweet chocolate, roughly chopped
8oz heavy cream
1/2 cup creamy peanut butter
1/2 cup Reese's peanut butter cups, roughly chopped
FROSTING:
1/2 cup creamy peanut butter
1/2 cup butter, at room temperature
2 tsp vanilla extract
2 cups powdered sugar