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Oatmeal Cream Pie Cake

Oatmeal Cream Pie Cake with tender oatmeal spice cake layers and a thick, fluffy marshmallow cream filling. Baked in two round pans and frosted for a classic oatmeal cream pie look with cinnamon-sugar style flavor.
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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 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
  • 1 stand mixer

Method
 

Bake the oatmeal cake layers
  1. Preheat oven to 350F and grease two 9-inch round pans for easy release and even baking.
  2. Beat butter and brown sugar until smooth, then add eggs, sour cream, and vanilla and mix until fully combined, glossy, and thick.
  3. Fold in flour, rolled oats, baking powder, baking soda, cinnamon, nutmeg, and salt until no dry streaks remain and the batter looks evenly speckled.
  4. Divide batter evenly between the two pans and bake for 30-35 minutes at 350F, until a toothpick in the center comes out clean or with a few moist crumbs.
  5. Cool the cakes completely in the pans before frosting so the filling stays thick and doesn’t melt.
Make and apply marshmallow cream filling
  1. Beat softened unsalted butter and cream cheese until smooth, then beat in marshmallow creme until the mixture turns silky.
  2. Add powdered sugar and vanilla and beat until very fluffy, holding soft peaks.
  3. Frost between the layers and spread the remaining marshmallow cream on the outside, smoothing with a flat spatula for a thick, even coat.

Notes

For the cleanest slices, cool the cakes completely (or chill 30-60 minutes) before frosting so the marshmallow cream stays plush and stable. Store covered in the refrigerator up to 4 days; freeze unfrosted cake layers up to 2 months, then thaw and frost. For a lighter option, replace half the butter with Greek yogurt (thick, plain) in the cake batter and expect a slightly softer crumb (filling still stays rich).