Preheat oven to 350°F and prepare three 8-inch cake pans with non-stick spray and parchment paper at the bottom.

In a large mixing bowl, combine flour, sugar, cocoa, baking powder, baking soda, and salt. Set aside.

In a medium bowl, mix together milk, vegetable oil, vanilla extract, and eggs.

Combine the wet ingredients with the dry mixture, beating until fully combined.

Gradually add the hot water to the batter, mixing on low speed until blended. Scrape down the bowl sides as needed.

Distribute the batter evenly among the prepared cake pans and bake for 22-25 minutes, or until a toothpick inserted comes out with a few moist crumbs.

Remove the cakes from the oven, let them cool for 2-3 minutes, then transfer to a cooling rack.

In a large mixer bowl, beat together butter and peanut butter until well blended.

Mix in half of the powdered sugar until smooth.

Add 3 tablespoons of milk or water, mixing until smooth.

Blend in the remaining powdered sugar until smooth.

Mix in the remaining milk or water, adjusting the consistency as needed to avoid it being too thin.

Use a serrated knife to level the tops of the cake layers.

Place the first cake layer on a serving plate or cake board. Spread about 1 cup of frosting evenly over the layer.

Sprinkle half of the chopped Reese’s over the frosting, pressing them in lightly. Add a thin layer of frosting on top to help the next layer stick.

Repeat with the second cake layer, spreading about 1 cup of frosting and the remaining chopped Reese’s.

Add the final cake layer on top.

Apply a thin crumb coat of frosting around the sides and top of the cake.

Spread about 1 cup of frosting evenly on top of the cake.

For a smooth finish, refer to a tutorial or use an offset spatula for the sides.

Set the cake aside to make the chocolate ganache.

Place the chocolate chips in a heat-proof bowl.

Heat the heavy cream in the microwave until it begins to boil, then pour over the chocolate chips. Let sit for 2-3 minutes, then whisk until smooth.

Drizzle the ganache over the cake edges with a spoon or squeeze bottle, then cover the top and smooth it with an offset spatula.

Allow the ganache to set for about 10 minutes.

Pipe swirls of the remaining frosting on top using a star tip. Garnish with halved Reese’s and crumbled Reese’s.

Refrigerate the cake until serving. Best served at room temperature and stays fresh for 3-4 days.