Step-by-Step Instructions
1. Make the Cake
Preheat your oven to 350°F and lightly grease a 13x18-inch sheet pan.
In a saucepan, combine water, peanut butter, butter, and oil. Heat until melted and smooth.
In a large bowl, whisk together flour, sugar, baking soda, and salt.
Pour the warm peanut butter mixture into the dry ingredients and mix until combined.
Stir in eggs, buttermilk, and vanilla extract. The batter will be slightly thin—that’s perfect.
Pour into the prepared pan and bake for 20–25 minutes, or until a toothpick inserted comes out clean.
2. Make the Frosting
In a saucepan, melt butter and peanut butter together until smooth.
Stir in milk and vanilla, then gradually whisk in powdered sugar until the frosting is thick yet pourable.
Spread the warm frosting evenly over the slightly cooled cake. The frosting will set into a soft, fudgy layer.
3. Slice and Enjoy
Let the cake cool fully before slicing into squares. Each bite is soft, nutty, and melt-in-your-mouth delicious.
Variations to Try
Chocolate Swirl: Drizzle melted chocolate over the frosting for a peanut butter cup vibe.
Crunch Factor: Sprinkle chopped peanuts or toffee bits on top for texture.
Peanut Butter & Jelly Twist: Add a thin layer of strawberry or raspberry jam between the cake and frosting.
Storage Tips
This cake stays fresh at room temperature for up to 3 days when covered. For longer storage, refrigerate up to 5 days or freeze slices individually for up to 2 months.
Final Thoughts
This Peanut Butter Sheet Cake with Peanut Butter Frosting is the kind of dessert that feels homemade and nostalgic, yet indulgent enough to impress guests. It’s simple, satisfying, and guaranteed to be a hit with anyone who loves peanut butter. Serve it at your next get-together, and don’t be surprised if people ask for seconds—and the recipe.
