1 cup (2 sticks) butter, at room temp
3/4 cup cornstarch
1/3 cup powdered sugar
1 cup all-purpose flour
Red and blue food coloring
Large chocolate nonpareils
In a large bowl, using an electric mixer set on low speed, beat butter until creamy. With mixer on medium speed, gradually beat in cornstarch and powdered sugar until fluffy.
Using a wooden spoon, stir in flour until a soft dough forms. Form dough into a ball; wrap in plastic wrap and chill for 1 hour.
Preheat over to 350 degrees. Divide dough in half. Tint one half the dough with red food coloring. Tint the remaining half with blue food coloring. Gently knead the colored doughs together for a swirled dough.
Roll swirled dough into 1-inch balls. Place dough balls 1 1/2-inches apart on an ungreased baking sheet. With the back of a spoon, press down on top of each dough ball to form a slight indentation.
Bake until cookies are firm to the touch but not browned, 10-12 minutes. Place chocolate nonpareils in the indentations of the warm cookies. Transfer cookies to wire rack; cool completely.