Combine melted butter and cocoa powder. Stir until smooth.
Cream brown sugar and white sugar with the butter/cocoa mixture.
Add eggs and vanilla.
Stir in salt, baking soda, and flour.
Mix in chocolate chips.
Chill dough for 1 hours.
Preheat oven to 350 degrees. Scoop dough (using a medium cookie scoop ---2 Tbsp.) and place on parchment paper-lined baking sheets.
Bake cookies for 10 minutes. Let cookies cool for 5 minutes on the pan before transferring to a wire rack.
Video
Notes
This recipe makes 2 ½ dozen cookies. Because they are so soft and chewy, I recommend storing them in a container in a single row or two, not stacking them in a cookie jar.