Step 1

Preheat oven to 300 degrees. Spray and 8 by 8-inch baking dish with non-stick cooking spray, set aside.

Step 2

Place butter in a large microwave safe bowl. Heat in microwave until just melted. Stir in sugar and salt, let cool slightly if warm.

Step 3

Add in eggs and vanilla. Break yolks and stir with wooden spoon just until blended.

Step 4

Add in flour, cocoa powder and chocolate chips. Fold and stir mixture with wooden spoon just until combined.

Step 5

Pour into prepared baking dish. Spread into an even layer. Bake in preheated oven just until barely set, about 40 - 55 minutes (toothpick may have a hint of sticky batter, be careful not to over-bake).

Step 6

Let cool completely on a wire rack before cutting into squares. Store in an airtight container at room temperature.