Combine flour, cocoa powder, baking soda and salt in a small bowl. Set aside.
Cream butter, brown sugar and granulated sugar until well combined, about 2 minutes. Add eggs. Beat until light and fluffy.
In a microwave safe bowl melt bittersweet chocolate chips on 50% power for 2 1/2 -3 minutes. Stir.
Add to creamed sugar mixture. Beat until fluffy about 2 minutes.
Gradually stir in flour mixture. Stir in semi sweet chocolate chips.
Drop by rounded spoonful, about 1 1/2 tablespoons onto baking sheets lined with parchment or silicone baking mats.