Preheat oven to 350F. Prepare a 9x13 baking dish with parchment paper or cooking spray.
In a mixing bowl combine the butter and sugar for 3-4 minutes until light and fluffy.
Add eggs and vanilla and mix until combined.
Add the flour and cornstarch and mix until just combined. Do not over mix!
Spread the cookie bar dough in the prepared baking dish in an even layer.
Bake at 350F for 15-20 minutes or until lightly browned on top.
Remove from the oven and cool completely.
While the cookie bars are baking, mix the frosting.
Cream the butter until light and fluffy.
Add the powdered sugar and mix until the flour is coated with butter.
Slowly add the milk until the frosting comes together.
Tint with food coloring if desired. Set aside until ready to frost the cookie bars.
Frost and add colored sprinkles if desired.
Cut and enjoy!
Notes
Be sure to let the cookie bars cool completely before frosting them or it will melt.
Pink frosting is always a hit for a baby shower or even Valentine's Day. Basically any special occasion.
If you want a richer frosting, you can use heavy cream instead of milk.
Measure the flour by fluffing it with a fork or spoon, spoon the flour into a measuring cup (don’t pack down), level with knife and then add to recipe.
If your frosting still seems too thin, add more powdered sugar, 1/4 cup at a time, until you get the consistency you want.
Change the colors and sprinkles on these sugar cookie bars to match any occasion!
You can mix in a stand mixer, electric mixer with a paddle attachment, or use a hand mixer.
Be sure to soften your butter at room temperature for at least 30 minutes before creaming. You want the butter soft and cool, not melted and warm.