This moist, deep, rich chocolate peanut butter cup cake is filled with a creamy, light peanut butter frosting and chopped peanut butter cups, and it’s topped with a luxurious chocolate ganache. Today I’m sharing one of my all-time favorite flavor combinations – peanut butter and chocolate. This Chocolate Peanut Butter Cup Cake is three layers of decadent cake, filled with a light and fluffy peanut butter frosting, and topped with chocolate ganache.