Oatmeal Cream Pie Bars
These Oatmeal Cream Pie Cookie Bars are a nostalgic twist on the classic treat, with a soft, chewy oatmeal cookie base and a fluffy marshmallow buttercream on top. A touch of molasses and cinnamon adds warm, cozy flavor in every bite. Perfect for sharing, gifting, or just treating yourself.
Ingredients
For the bars:
- 1 cup salted butter melted
- ⅔ cup light brown sugar
- ½ cup granulated sugar
- 2 tsp vanilla extract
- 1 tbsp unsulphured molasses
- 2 eggs room temperature
- 1 ½ cups all-purpose flour
- 1 tbsp corn starch
- 1 tsp baking soda
- 1 tsp ground cinnamon
- ½ tsp kosher salt
- 3 cups old fashioned oats You can also use quick oats for a softer, more uniform texture in the bars
For the frosting:
- ¾ cup salted butter room temperature
- 1 cup marshmallow creme
- 2 ½ cups powdered sugar
- 1 tsp vanilla extract
- ½ tsp salt
- 1-2 tbsp heavy cream or milk room temperature
- extra cinnamon for dusting the top
Instructions
For the bars:
- Preheat your oven to 350°F. Line a 9x13-inch pan with parchment paper and lightly grease. In a large mixing bowl, whisk together melted butter, brown sugar, granulated sugar, and molasses until smooth.
- Add eggs and vanilla and whisk again until fully combined. In a separate bowl, stir together the flour, cornstarch, baking soda, cinnamon, and salt. Add the dry ingredients to the wet ingredients and mix just until combined. Fold in the oats.
- Spread the dough evenly into the prepared pan and smooth the top. Bake for 25 minutes, or until the edges are golden and the center is just set. Let cool completely before frosting.
For the frosting:
- Beat the softened butter until smooth and creamy. Add the marshmallow creme and vanilla and beat until light and fluffy. Gradually mix in the powdered sugar and a pinch of salt. If needed, add a tablespoon or two of heavy cream for a spreadable consistency.
- Spread the marshmallow buttercream evenly over the cooled cookie bars. Lightly dust with ground cinnamon for that extra oatmeal pie magic.
- For cleaner slices, refrigerate the bars for 20–30 minutes before cutting into squares.