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Oatmeal Cream Pie Cake

Oatmeal cream pie cake with spiced oatmeal layers and a thick marshmallow cream filling, baked in two round pans and sandwiched for sliceable stacks. The cakes bake until set, then cool completely before frosting so the marshmallow cream stays smooth and fluffy.
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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: 512
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 softened
  • 1.5 cup brown sugar
  • 4 eggs
  • 1 cup sour cream
  • 2 tsp vanilla
For marshmallow cream filling
  • 0.5 cup butter softened
  • 4 oz cream cheese softened
  • 7 oz marshmallow creme 1 jar
  • 2 cup powdered sugar
  • 1 tsp vanilla

Equipment

  • 1 sheet pan
  • 1 stand mixer

Method
 

Bake the oatmeal cake layers
  1. Preheat oven to 350F and grease two 9-inch round pans so they release cleanly after baking.
  2. Beat 1 cup butter and 1-1/2 cups brown sugar until combined.
  3. Add 4 eggs, 1 cup sour cream, and 2 tsp vanilla, then beat again until the mixture looks smooth and cohesive.
  4. Fold in flour, rolled oats, baking powder, baking soda, cinnamon, nutmeg, and salt until no dry streaks remain.
  5. Divide the batter evenly between the two pans.
  6. Bake for 30-35 minutes, until a toothpick in the center comes out with just a few moist crumbs.
  7. Cool completely before frosting so the filling won’t melt or slide.
Make the marshmallow cream filling and assemble
  1. Beat 1/2 cup softened butter and 4 oz softened cream cheese until smooth.
  2. Add marshmallow creme and 2 cups powdered sugar and beat until thick.
  3. Beat in 1 tsp vanilla and continue until the frosting is very fluffy and spreadable.
  4. Frost between the layers first, then spread frosting on the outside for an even coating.

Notes

For clean slices, chill the assembled cake for 30-60 minutes after frosting. Store covered in the refrigerator for up to 4 days; freeze assembled or unfrosted cake layers up to 2 months (thaw overnight in the fridge). For a lighter option, use reduced-fat cream cheese in the filling and reduce powdered sugar slightly to keep the texture stable.