Cream butter and sugar in a bowl and mix with a hand mixer until fluffy, about 3 minutes.
Gradually mix in the flour.
Scoop the dough into heaped tablespoonfuls and roll into balls. Roll each ball of dough in sugar.
Place cookies onto an ungreased baking sheet, leaving 2 inches between each cookie. Flatten each ball of dough with the bottom of a glass. Decorate with sprinkles (if using).
Bake for 13-15 minutes. Cookies should still be soft in the middle.
Allow to cool on the baking sheet undisturbed for 20 minutes. Transfer to a cooling rack.
Notes
Baked cookies will keep at room temperature in an airtight container for 7 days and in the freezer for 4 months. Cookie dough will keep for 3 months in the freezer.