Step 1

Preheat oven to 350°F (180°C). Line baking sheets with parchment paper or silicone baking mats. Set aside.

Step 2

Combine the flour, baking soda, baking powder and salt in a medium sized bowl and set aside.

Step 3

Cream the butter and sugars together in a large mixer bowl on medium speed until light in color and fluffy. You should be able to see the change in color happen and know it’s ready.

Step 4

Add the egg and egg yolk and mix until well combined.

Step 5

Add the vanilla extract and mix until well combined.

Step 6

Add the dry ingredients to the wet ingredients and mix until the dough is well combined, but don’t over-mix. It will be thick and a little sticky.

Step 7

Fold in 1/2 cup of sprinkles, if you’re mixing them into your cookie dough.

Step 8

Create 1 1/2 tablespoon sized balls of cookie dough. Gently roll the dough into a ball, then roll each ball in the additional sprinkles to coat them, if desired. Set the balls on the baking sheet.

Step 9

Bake cookies for 7-9 minutes. The cookies will spread and the centers will look soft, but should look done. Don’t over-bake. The cookies will be a little puffy when you take them out of the oven but will fall a bit as they cool.

Step 10

Remove from the oven and allow to cool on baking sheets for 4-5 minutes before transferring to a wire rack to cool completely.