Step 1

Preheat oven to 350°F. Line a 9x13-inch baking pan with foil and spray with nonstick cooking spray.

Step 2

Place melted butter in the bowl of a stand mixer fitted with the paddle attachment (or a large bowl if using a hand mixer). You can also just use a wooden spoon to mix these! Add granulated and brown sugars and mix on low speed until the mixture is smooth. Mix in egg and vanilla extract and mix on medium speed until combined.

Step 3

Mix in cocoa, baking soda, and salt, then slowly mix in flour, and mix just until the batter is smooth and comes together. Be sure to scrape the sides of the bowl during mixing. Slowly mix in chocolate chips.

Step 4

Press dough into prepared pan. Bake for 19-24 minutes or until they just lose their glossy sheen. Cool completely before cutting.

Step 5

Store in an airtight container for up to 3 days or freeze for up to 3 months.