1. Prepare for Cake Baking:

• Preheat oven to 350°F (176°C).
• Grease three 8-inch round cake pans well. Line the bottoms with parchment paper circles and grease the parchment.
• In a large mixer bowl (or separate large bowl), whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt. Set aside.

2. Mix Cake Batter:

• In a separate medium bowl, whisk together the milk, vegetable oil, vanilla extract, and room temperature eggs.
• Add these wet ingredients to the dry ingredients in the mixer bowl. Beat on low speed until just combined, then increase speed slightly and beat until well combined.
• With the mixer on low speed, carefully and slowly add the hot water to the batter. Mix until well combined and smooth. Scrape down the sides and bottom of the bowl as needed.

3. Bake the Cake Layers:

• Divide the batter evenly between the three prepared cake pans.
• Bake for 22-25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs attached.
• Remove cakes from the oven and allow them to cool in the pans on wire racks for 2-3 minutes.
• Carefully invert the cakes onto the wire racks, remove the parchment paper, and allow them to cool completely (at least 1-2 hours).

4. Make the Peanut Butter Frosting (Inferred Steps):

• In the bowl of a stand mixer fitted with the paddle attachment (or using a hand mixer and large bowl), beat the room temperature salted butter and creamy peanut butter on medium-high speed until smooth and fluffy (2-3 minutes).
• Reduce the speed to low. Gradually add the sifted powdered sugar, alternating with the water or milk (starting and ending with sugar), until all ingredients are incorporated. Add liquid cautiously, just enough to reach desired consistency.
• Once combined, increase the speed to medium-high and beat for another 2-3 minutes until the frosting is very light and fluffy.
• Reserve about 1/3 of the frosting for filling. Gently fold the 6 chopped Reese’s cups into this portion. Keep the remaining 2/3 plain for frosting the outside.

5. Make the Chocolate Ganache (Inferred Steps):

• Place the semi-sweet chocolate chips in a small, heatproof bowl.
• Heat the heavy whipping cream in a small saucepan or in the microwave until it is hot and just beginning to simmer (do not boil).
• Pour the hot cream over the chocolate chips. Let sit for 5 minutes without stirring.
• Gently whisk the mixture until the chocolate is completely melted and the ganache is smooth and glossy. Let it cool slightly at room temperature until it’s thick enough to drip nicely down the side of the cake but still pourable (about 15-20 minutes, depending on room temp).

6. Assemble the Cake:

• If necessary, level the tops of the cooled cake layers with a long serrated knife.
• Place one cake layer on your serving plate or cake stand. Spread half of the Reese’s-filled frosting evenly over the top.
• Place the second cake layer on top and spread the remaining Reese’s-filled frosting evenly over it.
• Place the third cake layer on top.
• Use the plain peanut butter frosting to apply a thin crumb coat over the entire cake (top and sides). Chill for 15-20 minutes to set.
• Apply the remaining plain peanut butter frosting smoothly over the top and sides of the cake.

7. Add Ganache Drip and Decorate:

• Carefully spoon or pour the slightly cooled chocolate ganache around the top edge of the chilled cake, letting it drip down the sides naturally. You can control the drips by how much you pour and how close to the edge you start. Spread any remaining ganache thinly over the center top if desired.
• Arrange the 8 halved Reese’s cups around the top edge of the cake.
• Sprinkle crumbled Reese’s over the top center or around the base.

8. Serve and Store:

• For the best texture, let the cake sit at room temperature for at least 30 minutes before serving if it has been refrigerated.
• Store leftover cake in an airtight container. It can be kept at room temperature for a day or two, or refrigerated for longer storage (up to 4-5 days). Let slices come towards room temperature before eating for optimal flavor and texture.