Step 1

Step 1 Preheat your oven to 350 degrees F. Lightly grease an 8-inch cast iron skillet or 8-inch cake pan. Set aside.

Step 2

Step 2 In a small bowl, add the baking soda and salt and mix well to combined.

Step 3

Step 3 In the bowl of a kitchen mixer, such as a KitchenAid, fitted with a paddle attachment, add the sugar, brown sugar and butter and beat on high till fluffy. Reduce the speed and add the egg and egg yolk, scrapping down the sides as needed. Add the vanilla and mix to blend.

Step 4

Step 4 Add flour mixture and mix until blended. Remove the bowl from the stand and using a large rubber spatula, gently fold in the semi sweet chocolate chips.

Step 5

Step 5 Transfer the cookie dough to the prepared pan and use your spatula to spread evenly distributed in the skillet. Sprinkle half of the dark chocolate chips on top followed by the sprinkles.

Step 6

Step 6 Place in the oven and bake for about 25-30 minutes, or until the edges are puffed and browned and a cake tester inserted into the middle comes out clean.

Step 7

Step 7 Remove from the oven and press the remaining dark chocolate chips across the surface of the cookie. Allow to cool in the pan before serving.