GET READY: Preheat your oven to 375°F. Grease your cookie sheets nicely. Sift your flour and baking powder together in a medium bowl so there are no lumps.
CREAM & MIX: In a larger bowl, cream the butter and both sugars together. Add the eggs one at a time, then gently stir in the vanilla and your dry ingredients.
KNEAD: Lightly work the dough with your hands until it’s firm and loses its stickiness. If it feels a little too wet, just throw in a tiny pinch more flour.
CHILL: Time for a quick break! Wrap the dough and let it rest in the fridge for at least 1 hour.
SHAPE: Roll small amounts into 6-inch strips and twirl them into fun shapes, or just roll them into 1-inch balls and press down slightly.
BAKE: Pop them in the oven for 8 to 10 minutes. Keep a close eye on them—you want the bottoms to be a nice light brown, but keep the tops pale and light! Let them cool completely on a wire rack before you even touch the glaze.
GLAZE: Whisk your icing ingredients together. You want it thick enough to stay on the cookie, but runny enough to drip down the sides. Dip the tops into your cinnamon icing, let it drip, and throw your sprinkles on immediately while it's still wet.