Go Back

Oatmeal Cream Pie Cake

Oatmeal cream pie cake: a tall oatmeal spice layer cake with a thick pillowy marshmallow cream filling oozing between moist layers, then frosted in smooth vanilla cream. Topped with oatmeal cream pie cookie crumbles and a light powdered sugar dust for a nostalgic dessert cake look.
Print Recipe Pin Recipe
Prep Time 30 minutes
Cook Time 30 minutes
cooling 1 hour
Total Time 2 hours
Servings: 12 servings
Course: Dessert
Cuisine: American
Ingredients Equipment Method Notes

Ingredients
  

For the oatmeal cake
  • 2 cup all-purpose flour
  • 1.5 cup rolled oats blend fine
  • 1.5 cup brown sugar packed
  • 2 tsp cinnamon
  • 1 tsp baking soda
  • 1 tsp baking powder
  • 0.5 tsp salt
  • 3 eggs large
  • 1 cup buttermilk
  • 0.5 cup vegetable oil
  • 1 tsp vanilla extract
For the marshmallow cream filling
  • 0.5 cup butter 1 stick, softened
  • 2 cup powdered sugar
  • 1 can (7 oz) marshmallow fluff jar
  • 1 tsp vanilla extract
  • 2 tbsp heavy cream
  • 0.5 cup oatmeal cream pie cookies crumbeled, for garnish
  • 1 tbsp powdered sugar for dusting

Equipment

  • 2 sheet pan
  • 1 stand mixer

Method
 

Bake and cool the oatmeal cake layers
  1. Preheat oven to 350°F, grease two 9-inch round pans, and set aside.
  2. Whisk together all-purpose flour, blended rolled oats, packed brown sugar, cinnamon, baking soda, baking powder, and salt until evenly distributed.
  3. In a separate bowl, whisk together eggs, buttermilk, vegetable oil, and vanilla extract until smooth.
  4. Pour wet ingredients into dry ingredients and mix until smooth, with no dry pockets remaining.
  5. Divide batter between the two prepared pans and bake 28-32 minutes, until a toothpick comes out clean.
  6. Cool the cakes completely in the pans before assembling.
Make the marshmallow cream filling
  1. Beat softened butter until fluffy, using a stand mixer on medium speed.
  2. Add powdered sugar, marshmallow fluff, vanilla extract, and heavy cream, then beat until smooth and spreadable.
Assemble the cake
  1. Place one cake layer on a stand and spread the cream filling generously over the top.
  2. Place the second layer on top, then frost the outside with the remaining cream.
  3. Crumble oatmeal cream pie cookies over the top for garnish.
  4. Dust with powdered sugar and serve.

Notes

Pro tip: for clean layers and easy frosting, let the baked cakes cool fully until room temperature before spreading the marshmallow cream. Store covered in the refrigerator up to 3 days; the cake can be frozen up to 1 month (wrap well and thaw overnight in the fridge). For a dairy-reduced option, swap buttermilk with a dairy-free buttermilk alternative and use a dairy-free butter/margarine that creams well.