Cake Batter Blondies with Marshmallow Buttercream

For anyone who knows me, it's no secret that I love frosting. Love it. I can't get enough. So when I saw these on Cookies and Cups, with a new kind of buttercream (marshmallow!) I knew I had to try them. I actually made these a long time ago, well over a year I think, but I remember well how good they were. And with the gorgeous Tiffany-blue frosting, they look as great as they taste.

Cake Batter Blondies with Marshmallow Buttercream
Recipe from Cookies and Cups

Ingredients:
Blondies: 
1 box vanilla cake mix (I used Funfetti)
1/4 cup vegetable oil
1 egg
1/2 cup milk
1/2 cup white chocolate chips
1/2 cup mini marshmallows 

Frosting: 
1/2 cup butter, softened
1 cup Marshmallow Fluff
2 cups powdered sugar
2 Tbsp milk 
Food coloring, if desired

Directions:
Blondies: 
Preheat oven to 350°. Prepare a 9×9 pan with baking spray. In a large bowl, combine cake mix, vegetable oil, egg and milk until just combined. Batter will be dense. Stir in the white chocolate chips and marshmallows until distributed evenly. Spread the mixture in the prepared pan and bake for 25 minutes until center is just set. Cool completely.

Frosting: 
Mix butter and Fluff on medium speed until smooth. Slowly add in powdered sugar with mixer on low. Add in milk and turn speed up to medium and mix until all combined and smooth. Add food coloring, if desired, just a few drops at a time until the intended shade is reached. Spread the frosting over the cooled blondies, and top with sprinkles.