Preheat the oven to 350°F. Line 3 baking sheets with parchment paper or silicone baking mats.
Place the butter and sugars in the bowl of a stand mixer. Secure the paddle attachment and cream until light and fluffy, ~3 minutes.
12 Tbsp. unsalted butter, softened, 3/4 cup brown sugar, packed (dark or light), 1/2 cup granulated sugar
Then, add in the egg, egg yolk, and vanilla extract. Blend until mixed. If any of the mixture gets stuck on the paddle attachment or side of the bowl use a rubber spatula to knock it off.
1 large egg, room temperature, 1 large egg yolk, room temperature, 2 tsp. vanilla extract
Add in the dry ingredients and mix together on low speed.
2 cups all-purpose flour, spooned and leveled, 1 (3.4 oz.) package instant vanilla pudding mix, 1/2 tsp. baking soda, 1/2 tsp. baking powder, 1/2 tsp. salt
Add in the mini chocolate chips and fold in with a rubber spatula until combined.
1 1/4 cup mini chocolate chips
Scoop and roll into small balls (~1-2 tsp in size) and place on the prepared baking sheets. You should be able to fit ~24 cookies on each baking sheet.
Bake for just 5-6 minutes, the cookies will begin to turn a little golden around the edges and the tops might look a little under done, but that's perfect. They'll continue to bake on the sheet pan once you pull them out of the oven. Garnish with more mini chocolate chips on top, if desired. Cool on the cookie sheet for a few minutes then carefully transfer to a wire rack.
And that's it! Good luck eating just one! 😉