Step 1

Preheat your oven to 375 degrees F. Line a 9-inch x 13-inch metal pan with parchment paper, use enough paper so that it's hanging over the sides. (This will make it easier to remove the cookie bars from the pan later.) Set aside.

Step 2

In the bowl of a stand mixer, mix butter, sugar, and powdered sugar for 3 minutes on medium speed. Add the eggs and vanilla and mix again until combined.

Step 3

In a medium mixing bowl, stir together the all-purpose flour, salt, and baking powder. Add the dry ingredients to the wet ingredients and mix for about 1 minute on medium.

Step 4

With a rubber spatula, fold in the sprinkles. (I find adding 2 TBSP at a time can allow for an easier distribution. Just don't mix too much of the colors will start to bleed into the cookie dough.)

Step 5

Trasnfer the cookie dough to the prepared pan and press into an even layer.

Step 6

Bake for 12-15 minutes or until the edges are just starting to lightly brown.

Step 7

Remove from the oven and allow to cool completely in the pan, about 2 hours.

Step 8

Once the cookies are cooled, beat the butter, sugar, and salt together until combined. Add in 1 tablespoon of heavy cream and mix medium-high for about 2 minutes. (You can add another tablespoon of heavy cream to thin out the frosting if needed.)

Step 9

Spread the frosting over the cookie bars, edge to edge, and then top with more sprinkles. Cut into 24 bars and enjoy!