Ingredients

1 cup unsalted butter, softened to room temperature
1 cup powdered sugar
2 tsp. vanilla
2 1/2 cups all purpose flour
1/2 tsp. salt
Rainbow sprinkles

For the Frosting:
3/4 cup powdered sugar
1 Tbs. corn syrup
1/4 tsp. vanilla
1 Tbs. unsalted butter, melted
1-2 Tbs. milk (to thin to desired thickness)

Directions

For the Cookie:
Preheat the oven to 350 and prepare two baking sheets by lining them with parchment paper. Place sprinkles into a bowl. Set everything aside.

In a large bowl and using a hand mixer, cream butter, sugar, and vanilla together until light and fluffy (2-3 minutes). Add the salt to the butter mixture, and slowly (in 3-4 batches) add the flour, mixing in between each addition. Mix until flour is completely incorporated into the dough. Dough is ready when a scoop of dough will stay together after being rolled into a ball.

Scoop out even tablespoons of dough, roll them into a ball, and then roll the ball in the sprinkles. Place balls onto the prepared baking sheets at least 1 1/2-2 inches apart. Make a slight indent in the top of each ball with your thumb or the end of a round kitchen tool. (do not completely press the cookies flat, because they will crack)

Bake cookies for 10 minutes. Remove the cookies from the oven and make a deeper indent in the tops of each cookie using the end of a kitchen tool. Bake for 7-8 more minutes, or until the cookies are set but the edges are not browned.

Allow the cookies to cool completely before frosting.

For the Frosting:
Mix powdered sugar, corn syrup, vanilla, unsalted butter, and 1 Tbs. of milk together in a bowl. Add enough milk to make the frosting thin enough to pour into the center of the cookies, but not so thin that it is runny (you will not need more than 2 Tbs. of milk).

Drop a spoonful of the frosting into the center of each cookie and allow it to set before serving.