These soft and chewy Frosted Sugar Cookie Bars are the perfect kid-friendly dessert that the whole family will love! Super soft sugar cookie bars piled with vanilla buttercream frosting and lots of sprinkles! So easy to bake since they’re in bar form!
Preheat oven to 350-degrees. Line a 8 or 9-inch square pan with foil. Set aside.
Place butter in a large mixing bowl. Beat for 1 minute until light and creamy.
Add sugar to butter. Cream together until light and fluffy.
Add egg, egg yolk, and vanilla. Beat until combined. Set aside.
In a separate bowl, add dry ingredients (flour, corn starch, baking powder, baking soda, and salt). Whisk to combine.
Pour about a third of the flour mixture into the butter mixture. Mix on low until combined. Repeat twice more with the remaining flour mixture. The mixture will be very thick.
Fold in sprinkles.
Press dough into square pan.
Bake at 350-degrees for about 25-26 minutes (not too long so they'll be nice and soft).
When bars are done cooking, allow to cool to room temperature. Frost. Top with sprinkles and cut into 16 squares.
Notes
This recipe makes a square pan of 16 bars, but you can easily double it and bake it in 9"x13". The cooking time will change to 30-35 minutes.NOTE: Use rainbow jimmies in the sugar cookie bars. NOT nonpareils. The nonpareils will bleed and turn your cookie bars weird colors. But they're perfectly pretty to use for decorating on top!