Preheat oven to 350°F (175°C) and line a baking sheet with parchment.

In a large bowl, whisk flour, cocoa, baking soda, and salt.

Add butter and both sugars; beat until coarse and combined.

Stir in egg and vanilla until blended. Fold in chocolate chips.

Scoop tablespoon-sized mounds onto the sheet, spacing 2 inches apart.

Bake 9–11 minutes until set at the edges but still soft in the center. Cool on a rack.