Step 1

Preheat oven to 325 degrees. Line a 8x8 inch pan with parchment or foil, set aside.

Step 2

In a microwave safe bowl, add the butter and sugar. Heat in the microwave on HIGH for about 1 minute and 15 seconds. Remove, stir, and cool on the counter for 5 minutes, then stir in the vanilla extract and cocoa powder.

Step 3

In the bowl of a stand mixer add the warm (but not hot) butter/sugar mixture. With mixing speed on low add one egg at a time, mixing just until incorporated.

Step 4

In a medium size mixing bowl, whisk together flour, baking soda, cornstarch, and salt. With mixing speed on low, gradually add dry ingredients. Mix until no flour pockets remain. Remove bowl from stand and fold in the chocolate chips and chunks.

Step 5

Spread the brownie batter evenly into the prepared pan. Place in the oven and bake for 20-30 minutes or until the brownies are set. Remove from oven and allow to cool for 30-45 minutes before cutting and serving.