Preheat oven to 350 degrees F. Line baking sheets with parchment paper. Set aside.
Add butter, sugar, and vanilla extract to the bowl of your stand mixer, fitted with the paddle attachment. Beat on medium speed until light and fluffy, about 3 minutes.
¾ cup unsalted butter, 1 cup granulated sugar, 1 teaspoon vanilla extract
Add in egg and mix until just combined.
1 large egg
Add flour, baking powder, and salt. Stir in until just combined.
2 ¼ cups all purpose flour, 1 teaspoon baking powder, ½ teaspoon salt
Add the sprinkles and carefully stir again until combined, but make sure not to crush the sprinkles too much.
½ cup rainbow jimmy sprinkles
Scoop dough into 1 ½ tablespoon sized portions and roll into balls. Place on the prepared baking sheets, leaving about 2 inches between each one.
Top each dough with a small pinch of additional sprinkles.
Bake for 10-15 minutes or until lightly golden brown around the edges.
Notes
Butter: If using salted butter, reduce the salt to 1/4 teaspoon.
Vanilla: For stronger vanilla flavor, increase the vanilla extract to 2 teaspoons.
Flour: To properly measure the flour, I recommend weighing it (click "metric" just above the ingredients) or sift, lightly spoon into the measuring cup, and level.
Sprinkles: I've had good luck with Betty Crocker sprinkles as they don't bleed in baked good.