1 stick (1/2 c.) salted butter, softened
1 lb. confectioners' sugar, plus extra for dusting
2 Tbsp. heavy cream
1 tsp. mint extract
2-3 liquid food colors
In a large bowl, beat butter until creamy. With mixer on low, beat in sugar, cream, and extract until creamy and smooth. Turn sugar mixture out onto a work surface lightly dusted with confectioners' sugar; knead until smooth and satiny. Divide mixture into thirds. Tint each a different color with the food coloring; if you want, you can leave one portion white. Cover each portion with a towel or plastic wrap to keep them from drying out.
Line a baking sheet with foil.
Lightly dust work surface with confectioners sugar. Working with one color at a time, roll out 1/4 cupfuls of the mint mixture, using your fingers, into a 1/2-in thick rope. Cut rope into 1/2-in candies. Transfer mints to baking sheet with a spatula (be careful, they squish easily). Repeat with remaining mint mixture.
Let air-dry at room temperature for 1-2 days until firm enough to handle. Transfer mints to covered containers.