One-Bowl Chocolate Peanut Butter Sheet Cake

By , Test Kitchen Director · Reviewed by AislePrompt Editorial · ·

A moist chocolate sheet cake swirled with peanut butter, baked in one bowl for easy preparation and indulgent flavor. This american-inspired desserts ready in about 55 minutes layers all-purpose flour, granulated sugar, unsweetened cocoa powder into a dessert worth slowing down for — great for weekend baking, holiday tables, or any time you want a sweet payoff at the end of a meal. Each serving lands at about 320 calories and feeds 12, so it slots into a weekend bake or a special-occasion dessert tray. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

Prep: 15 min Cook: 40 min Serves 12 American cuisine 320 cal/serving
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Ingredients

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Instructions

  1. Step 1: Preheat the oven to 350°F. Grease and flour a 9x13-inch baking pan.
  2. Step 2: In a large mixing bowl, whisk together 1 3/4 cups all-purpose flour, 2 cups granulated sugar, 3/4 cup unsweetened cocoa powder, 1 1/2 teaspoons baking soda, and 1 teaspoon salt until well combined.
  3. Step 3: Add 1 cup buttermilk, 1/2 cup vegetable oil, 2 large eggs, and 2 teaspoons vanilla extract to the dry ingredients. Beat with an electric mixer on medium speed for 2 minutes until smooth.
  4. Step 4: Gradually stir in 1 cup hot water (batter will be thin) until fully incorporated.
  5. Step 5: Pour the batter evenly into the prepared pan.
  6. Step 6: Drop spoonfuls of 1/2 cup creamy peanut butter over the top of the batter. Use a knife or skewer to swirl the peanut butter gently through the batter to create a marbled effect.
  7. Step 7: Bake for 35-40 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
  8. Step 8: Let the cake cool completely in the pan before slicing and serving.

Frequently asked questions

How long does One-Bowl Chocolate Peanut Butter Sheet Cake take to make?

Total time is about 55 minutes (15 min prep + 40 min cook). Most home bakers find this fits a weekend afternoon; chill or store as the recipe directs before serving.

How do I store leftover One-Bowl Chocolate Peanut Butter Sheet Cake?

Cool fully before storing. Most baked desserts keep at room temperature in an airtight container for 2–3 days, or in the fridge for up to 5 days. Cream- or custard-based desserts must go in the fridge within 2 hours; reheat gently or serve cold per the recipe.

Can I substitute ingredients in One-Bowl Chocolate Peanut Butter Sheet Cake?

Yes — most ingredients in this recipe have flexible swaps. For oil, use any neutral high-smoke-point oil (avocado, grapeseed, refined coconut). For aromatics, dried herbs at ⅓ the volume of fresh work in a pinch. The full ingredient list is shoppable on Instacart so you can see substitutes in real time.

How do I scale One-Bowl Chocolate Peanut Butter Sheet Cake for a different number of people?

The recipe is written for 12 servings. Multiply each ingredient by (your serving target / 12). Cook time stays roughly the same up to 2x; for 3-4x batches, switch from a skillet to a sheet pan or stockpot so the food isn't crowded — overcrowding steams instead of browns.

What goes well with One-Bowl Chocolate Peanut Butter Sheet Cake?

American desserts like this pair well with a simple grain (rice, couscous, or crusty bread), a quick salad with acid (lemon vinaigrette, pickled onions), and a pan sauce or yogurt-based dip. Tap "Plan a meal with the AI" to get specific side suggestions.

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