Preheat oven to 350°F; line two baking sheets with parchment.
Whisk flour, cocoa, baking soda, and salt in a medium bowl.
Beat butter and both sugars in a large bowl about 2-3 minutes, until creamy and smooth.
Beat in eggs and vanilla until well combined and fluffy.
Gradually mix in dry ingredients just until combined; fold in both chocolate chips.
Drop rounded tablespoons onto prepared sheets, 2 inches apart.
Bake 10-11 minutes, until edges set and centers look slightly soft and underdone.
Cool on sheet 5 minutes; transfer to wire rack to cool completely.