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Oatmeal Cream Pie Cake

Oatmeal Cream Pie Cake is baked as tender oatmeal spice layers and stacked with a thick, marshmallow-cream filling. The cake bakes in two 9-inch rounds, then gets a smooth, fluffy frosting between layers and all over the outside.
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Prep Time 35 minutes
Cook Time 35 minutes
Total Time 1 hour 10 minutes
Servings: 12 servings
Course: Dessert
Cuisine: American
Calories: 520
Ingredients Equipment Method Notes

Ingredients
  

For oatmeal cake layers
  • 2 cup flour
  • 1.5 cup rolled oats
  • 1 tsp baking powder
  • 0.5 tsp baking soda
  • 2 tsp cinnamon
  • 0.5 tsp nutmeg
  • 0.5 tsp salt
  • 1 cup butter
  • 1.5 cup brown sugar
  • 4 eggs
  • 1 cup sour cream
  • 2 tsp vanilla
For marshmallow cream filling
  • 0.5 cup unsalted butter
  • 4 oz cream cheese
  • 1 can (7 oz) marshmallow creme
  • 2 cup powdered sugar
  • 1 tsp vanilla

Equipment

  • 1 sheet pan

Method
 

Bake the oatmeal cake layers
  1. Preheat oven to 350F and grease two 9-inch round pans. This helps the layers release cleanly after baking.
  2. Beat butter and brown sugar until combined. Mix in eggs, sour cream, and vanilla until smooth.
  3. Fold in flour, rolled oats, baking powder, baking soda, cinnamon, nutmeg, and salt. Mix just until no dry streaks remain.
  4. Divide the batter between the two pans. Bake at 350F for 30-35 minutes, until the centers spring back lightly.
  5. Cool the cakes completely before frosting. Cooling fully prevents melting the filling.
Make and apply marshmallow cream filling
  1. Beat softened unsalted butter and softened cream cheese until smooth. Add marshmallow creme and beat again until creamy.
  2. Beat in powdered sugar and vanilla until the filling is smooth and very fluffy. Scrape the bowl as needed for an even texture.
  3. Frost between the cake layers using a generous layer of marshmallow cream filling. Press the layers together lightly so the filling spreads to the edges.
  4. Frost the top and outside of the cake with the remaining filling. Smooth the surface and chill briefly only if needed to firm up for clean slices.

Notes

Pro tip: Cool the baked layers completely (not just warm) before frosting so the marshmallow cream stays thick and fluffy. Store the cake covered in the refrigerator for up to 4 days; freeze frosted slices up to 2 months for best quality. For a lighter option, use low-fat cream cheese in the filling—texture will be slightly softer but still flavorful.