Ingredients
For the Cake Base
1 box devil’s food chocolate cake mix (about 15.25 oz / 430 g)Groceries
1 cup whole milk (or water, per cake mix instructions)
½ cup vegetable oil
3 large eggs
(Alternatively, you can use your favorite homemade chocolate cake batter — just ensure it’s pourable.)
For the Cream Cheese Mixture
1 package (8 oz / 225 g) cream cheese, softened
½ cup (115 g) unsalted butter, melted
3 ½ cups powdered sugar, sifted
½ cup creamy peanut butter
For the Peanut Butter-Chocolate Add-Ins
1 cup Reese’s Peanut Butter Cups, roughly chopped
¾ cup Reese’s Pieces candies
½ cup peanut butter chips
½ cup semi-sweet or milk chocolate chips
Optional: a pinch of sea salt flakes for topping
Step-by-Step Instructions
Cream cheese
Step 1 – Preheat and Prepare the Pan
Preheat your oven to 350°F (175°C).
Grease a 9×13-inch (23×33 cm) baking pan generously with butter or nonstick spray.
You can also line it with parchment paper for easier cleanup.
Step 2 – Prepare the Cake Batter
In a large bowl, combine:
The box of devil’s food cake mix
Milk (or water, per package)
Oil
Eggs
Whisk or beat until smooth and lump-free.
Set aside while preparing the filling.
The batter should be glossy and slightly thick — this will form the base layer.
Step 3 – Prepare the Cream Cheese Filling
In a separate bowl:
Beat softened cream cheese with melted butter until smooth.
Add peanut butter and beat until creamy.
Gradually add powdered sugar, one cup at a time, mixing until fully combined and silky.
This mixture should be rich and spreadable — like thick frosting.
It’s this layer that creates the “earthquake” effect when baked.
Step 4 – Assemble the Layers
Peanut butter
Now comes the fun part — layering and “messing up” the cake on purpose!
Pour the chocolate cake batter evenly into your prepared pan.
Sprinkle half of the Reese’s Peanut Butter Cups, Reese’s Pieces, and peanut butter chips over the batter.
Spoon the cream cheese mixture in large dollops across the surface (don’t spread it evenly — you want some thick pockets).
Sprinkle the remaining candies and chips over the top.
Step 5 – Bake
Place the cake in the oven and bake for 45–50 minutes, or until the edges are set and the center is slightly gooey.
Because of the cream cheese mixture, a traditional toothpick test won’t be accurate — it should come out with some moist crumbs attached.
As it bakes, you’ll notice cracks forming on top and patches of cream cheese peeking through — that’s exactly what you want!
Step 6 – Cool Before Serving
Let the cake cool for at least 30 minutes before slicing.
It will firm up slightly but stay wonderfully gooey inside.
You can serve it warm for a molten texture or chilled for a dense, fudgy version.
