Preheat the oven to 350º Fahrenheit.

Prepare a baking sheet by lining it with parchment paper and set aside.

In a large mixing bowl, cream butter and sugar together with a hand mixer until light and fluffy.

Add egg, milk, and vanilla. Mix again until smooth.

Add flour, baking powder, and salt. Mix until dough forms.

Roll dough into 1-inch balls and place them onto a prepare baking sheet.

Using a glass dipped in flour, press each dough ball down until it is about 1/2-inch thick.

Bake for 9 minutes or until tops begin to brown.

Allow cookies to cool completely.

Whisk powdered sugar, milk, and vanilla together. If icing is too thick, add more milk a little at a time until it reaches desired consistency. If icing is too thin, add more powdered sugar.

Split icing between 4 small bowls then add 2 drops of color food coloring to each bowl, creating 4 different colored icing. Dipped cooled cookies into icing.

Immediately add sprinkles of your choice.

Allow icing to harden and serve.

Store in an airtight container.