In a large bowl whisk up the box of cake mix, melted butter, 3 eggs, and brewed coffee.
Chop the Reeses Peanut Butter Cups into 1/2 inch pieces and fold into the mixture. (you can sprinkle a tsp. of flour on the Reeces chunks and mix together before adding if you want them to stay elevated in the cake) otherwise it'll be more like a crust at the bottom (like I did)
Spray the crockpot liberally with a nonstick spray.
Pour in the cake mix, cover the crockpot, and set to high and cook for about 2 hours.
Once the cake is done make the peanut butter drizzle:
in a sauce pan add the heavy cream and peanut butter and mix together at low heat just until it's incorporated. Then, mix in the powdered sugar. Remove from heat once it's incorporated.
Then you have 2 options:
Ice the cake with the peanut butter drizzle fully OR
do what I did which was cut the cake in chunks and serve with the peanut butter sauce drizzled on top.
Garnish with whipped cream and halved Reeses Cups! ENJOY! Make IT!