Line 8x8 pan with parchment paper
Cover loosely & microwave 30 seconds, stir & microwave another 15 seconds more to melt the butter & chocolate.
Add sugars, stir until completely dissolved. Let the mixture cool to room temperature.
Add in eggs
Fold in flour, cocoa, salt, & vanilla just until all white streaks are gone. Then fold in chocolate chips.
Pour into prepared pan
Bake 28-30 minutes or until toothpick test is clean