Step 1

Preheat oven to 350°F and spray a 9x13" pan with cooking spray.

Step 2

In the bowl of a stand mixer, add the butter, brown sugar and sugar; mix until light and fluffy.

Step 3

Add the eggs and vanilla and mix until well-combined, scraping down the sides of the bowl halfway through.

Step 4

Add the flour, baking soda and salt and mix until incorporated.

Step 5

Add 1 cup of the semi-sweet chocolate chips (save the rest for the top) and the milk chocolate chips and stir.

Step 6

Spread the cookie dough into the prepared pan and smooth out the top.

Step 7

Sprinkle remaining chocolate chips on top.

Step 8

Bake for 22-26 minutes, or until the edges are a light golden-brown.

Step 9

Let cool, then cut into squares and enjoy!