Fun, colorful, SPRINKLE COOKIES! No chilling required! Buttery chewy cookies encased in a colorful sprinkle shell! Be sure to check out the how-to VIDEO at the bottom of the post!
Preheat oven to 350F (175C) and line several baking sheets with parchment paper. Set aside.
In a large bowl and using an electric mixer, or in the bowl of a stand mixer, cream together butter and sugar until well-combined
Add egg and egg yolk and vanilla extract. Beat until thoroughly combined.
In a separate, medium-sized bowl, whisk together flour, cream of tartar, cornstarch, baking soda, and salt until completely combined.
Gradually add dry ingredients to wet until completely combined.
Scoop dough into Tablespoon-sized balls and roll between your palms until smooth and round. Immediately roll through nonpareils until cookie dough ball is completely coated with sprinkles.
Place on prepared baking sheet, spacing cookies at least 1 ½” apart.
Transfer to 350F (175C) preheated oven and bake for 9-10 minutes. Allow to cool completely on baking sheet before serving.