Start by browning the butter. Place 1 cup + 3 tablespoons of unsalted butter in a medium pan over medium-low heat and melt the butter.
3 tablespoons unsalted butter, 1 cup unsalted butter
Once melted, increase the heat to medium and let the butter begin to foam. Keep cooking and stirring with a spatula, until the milk solids begin to brown and gives off a nutty smell (2-3 minutes).
Pour into a medium bowl or jug and let come to room temperature. Once cooled down, place in the fridge. Let it firm up, but it should be soft to the touch (like room temperature butter!)
Preheat your oven to 350°F/175°C. Line your baking sheet with parchment paper.
In a medium bowl, whisk together the flour, baking powder and salt together. Set aside.
2 ¾ cups all purpose flour, 2 teaspoon baking powder, 1 teaspoon kosher salt
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter for 1 minute until soft and creamy.
Add your sugar and beat on medium-high for 3 minutes until light and fluffy.
1 ¾ cups sugar
Add your egg, egg yolk, and vanilla extract, then beat until it is well combined.
1 egg, 1 egg yolk, 2 teaspoon vanilla extract
Add your dry ingredients and beat on low, stop as soon as the flour is combined.
Pour in your sprinkles and fold by hand.
½ cup sprinkles
Scoop out the dough into 1 ½ tablespoon balls and roll in the extra granulated sugar. Chill for 20 minutes or up to overnight. If chilling overnight, keep the cookie dough balls in an airtight container or wrap in plastic wrap.
½ cup sugar
Bake 4-6 at a time (depending on the size of your baking sheet!) for 11 minutes. While you're baking those, keep the others in the fridge. The cookies will continue cooking when they’re taken out of the oven and the middle will set and crack.
Notes
My recipes have been developed and tested in metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way. Just click on ‘Metric’ above the ingredients. Butter: I use European style butter which will make your cookies extra creamy and buttery. You'll need 271 grams or 1 cup and 3 tablespoons of butter. Sprinkles: I do not recommend using nonpareil sprinkles (those tiny circular balls) as they might bleed in the batter and won't show up. Storage: keep the baked cookies in an airtight container for up to 5 days at room temperature. Freeze unbaked cookie dough balls, when ready to bake just bake for an extra minute or two.