Best Oatmeal Peanut Butter Cup Cake
Submitted by ib6ub9
Oatmeal sheet cake with peanut butter cups baked on top and chocolate frosting. A nostalgic 13×9 dessert that hides peanut butter pockets in every bite.
YIELD
18 servingsPREP
20 minCOOK
60 minREADY
80 minThis is an old-fashioned oatmeal sheet cake with peanut butter cups baked into the top, finished with a glossy chocolate frosting. The combination is nostalgic and crowd-pleasing: a moist, slightly chewy oat-based cake studded with melty peanut butter cup chunks and crowned with chocolate.
The boiling-water-on-oats step at the start is the recipe’s foundation. Pouring boiling water over rolled oats and letting them cool softens them into a porridge that adds moisture and tenderness to the cake. Skip this step or substitute dry oats and you get a coarse, crumbly cake instead of the soft texture this recipe is built for.
The “sprinkle peanut butter cups, do NOT stir” instruction is critical. Stirring the chopped candy into the batter buries it; sprinkling on top means the candy partially melts into the cake’s surface during baking, creating crackled chocolate and peanut butter pockets visible from above.
Cool the cake fully before frosting. Warm cake melts the buttercream and turns it slick; cooled cake holds the frosting cleanly.
The frosting is a quick chocolate buttercream made by melting unsweetened chocolate with butter, then beating in powdered sugar, milk, and vanilla. Chill 15 minutes to spreading consistency before frosting; warm frosting is too loose to hold shape on top.
Pro Tips
- Use 5 standard peanut butter cups, chopped roughly. The recipe is specific about this; substituting Reese’s Pieces or chips changes the dish.
- Quick oats work better than old-fashioned in this recipe; they soften faster in the boiling water and integrate smoothly into the batter.
- Test for doneness with a toothpick at 40 minutes. With melted candy on top, ovens vary; pull when a toothpick from the cake (not a candy pocket) comes out clean.
- Cut and serve from the pan. Sheet cakes don’t unmold well; this is a “cut squares straight from the dish” cake.
Variations
- Substitute mini Reese’s cups for the chopped full-size cups for more even distribution.
- Swap unsweetened chocolate for semi-sweet in the frosting and reduce powdered sugar by ½ cup for a less sweet finish.
- Add ½ cup chopped peanuts to the batter for crunch alongside the peanut butter cup pockets.
Ingredients
Directions
- Use 5 (6 ounce size) milk chocolate covered peanut butter cups.
Combine water and rolled oats; cool to room temp; set aside.
Cream together butter, brown sugar, sugar and vanilla; beat in eggs.
Blend in oatmeal mixture.
Combine flour, baking soda, baking powder, cinnamon and salt; add to creamed mixture.
Beat 1 minute on medium speed.
Pour batter into a greased and floured 13×9×2-inch pan.
Chop peanut butter cups and sprinkle on top of batter.
Do NOT stir. Bake at 350℉ (180℃) for 40 to 45 minutes or until cake tests done.
Let cake cool completely before frosting.
For Frosting.
Melt butter in small saucepan. Add chocolate and stir constantly over very low heat until melted.
Pour into small bowl.
Add remaining ingredients and beat until well blended.
Chill to spreading consistency, about 15 minutes.
Frost cake.
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