Preheat the oven to 350° degrees F and prepare a baking sheet lined with parchment paper.
In a large mixing bowl with an electric mixer or hand mixer, cream together room temperature butter and granulated sugar for 2-3 minutes, or until light and fluffy.
Add the egg, vanilla extract and almond extract and mix until incorporated.
In a separate mixing bowl, combine together flour, baking powder, baking soda, cornstarch and salt. Slowly add the dry ingredients to the creamed mixture. Mix until just incorporated.
Stir in the rainbow sprinkles.
Scoop out dough In 1 tablespoon balls. Place on baking sheet.
Bake for 10-12 minutes. They will be set but still slightly undercooked in the middle, they will continue baking when removed from oven.