Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
In a bowl, whisk together flour, cocoa powder, baking soda, and salt.
In a separate bowl, mix melted butter with granulated and brown sugars until smooth.
Add eggs one at a time, then stir in vanilla extract.
Gradually add the dry ingredients to the wet ingredients and mix until just combined.
Fold in the chocolate chips.
Chill dough for 30 minutes to improve texture and flavor.
Scoop dough onto baking sheets, spacing about 2 inches apart.
Bake for 10–12 minutes, until edges are set and centers still look soft.
Let cool on the baking sheet for 5 minutes, then transfer to a wire rack.