- 1 1/2 cups all-purpose flour
- 1 teaspoon baking powder
- 1 teaspoon cream of tartar
- 1/2 teaspoon baking soda
- 1/2 teaspoon salt
- 1/2 cup (1 stick) unsalted butter, at room temperature
- 3/4 cup granulated sugar
- 1 vanilla bean
- 1 large egg
- 1 teaspoon pure vanilla extract
- 1/2 cup sprinkles (I prefer jimmies over nonpareils)
- In a medium bowl whisk together flour, baking powder, cream of tartar, baking soda, and salt.
- In the bowl of an electric mixer fitted with a paddle attachment, beat the butter and sugar at medium speed until light and fluffy, about 3 to 4 minutes. Split the vanilla bean and scrape the seeds into the bowl. Add the egg and vanilla extract, and beat until thoroughly combined.
- Reduce the mixer speed to low, and slowly add the dry ingredients into the wet ingredients. The dough will be thick (you may have to finish incorporating the mixture with a spatula). Fold in 1/4 cup of the sprinkles.
- Place the remaining 1/4 cup sprinkles in a bowl. Scoop up 2 tablespoons of dough and roll into a ball. Dip the ball in the bowl of sprinkles to cover lightly. Put the balls on a plate. Repeat with the remaining sprinkles and dough. Chill the dough for at least 2 hours.
- Place racks in the center and upper third of the oven and preheat the oven to 350 degrees F. Line 2 baking sheets with parchment paper.
- Transfer the chilled dough balls to the prepared baking sheets, leaving about 2 inches of space in between each ball.
- Bake until the cookies have spread and are just beginning to brown around the edges, but are mostly pale and soft, 8 to 10 minutes. Let cool on the cookie sheets for 5 minutes before transferring to wire racks to cool completely. The cookies will keep in an airtight container for up to 4 days.