Preheat the oven to 350 degrees.
In a mixing bowl add cake mix, dry pudding, water, and oil.
Add eggs one at a time mixing very well. The batter should be smooth and shiny before adding the next egg. Repeat until all eggs have been added.
Add the vanilla and beat for 3-4 more minutes.
Grease two 8 inch round baking pans. Pour batter into each baking pan. Putting an even amount in both pans.
Bake for 20-25 minutes or until a toothpick comes out clean.
Cool completely before icing the cake.
Spread icing on the cooled cake. Top with the mini peanut butter cups. Keep refrigerated.