In a large mixing bowl, mix together the softened butter, granulated sugar, and brown sugar until the mixture is light and fluffy

Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.

In a separate bowl, whisk together the all-purpose flour, cocoa powder, baking soda, and salt

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not to overmix.

Fold in the chocolate chips until they are evenly distributed throughout the cookie dough.

Drop rounded tablespoons of dough onto the prepared baking sheets, spacing them about 2 inches apart and keep in the fridge for 30mins

Bake in the preheated oven 180°C for 12 minutes, until the edges are set but the centers are still soft. The cookies will continue to firm up as they cool.