Preheat oven to 350 Fahrenheit. Line a 9x13" pan with parchment paper and grease well (I use cooking spray).
Whisk together dry ingredients and set aside.
Stir butter with sugars. Slowly stir in eggs and vanilla.
Add combined dry ingredients to wet. Mix until just incorporated.
Fold in 3/4 c. of the chocolate chunks (reserving 1/2 c. for the top). Pour into the prepared 9x13" greased pan.
Sprinkle remaining 1/2 c. of chocolate chunks on top of batter.
Bake for 26-28 minutes until set. Remove from oven and let rest 20 minutes for before eating, to allow brownies to finish cooking and set up.