Preheat your oven to 350°F (175°C).
Line a 9x13-inch baking pan with parchment paper.
In a large mixing bowl, whisk together the melted butter, granulated sugar, and brown sugar until well combined. Add in the eggs and vanilla extract, mixing until smooth.
In another bowl, sift together the cocoa powder, baking soda, salt, and all-purpose flour.
Gradually add the dry ingredients to the wet ingredients, stirring gently with a spatula until just combined.
Gently fold in the chocolate chips until evenly distributed.
Pour the batter into the prepared baking pan and spread it out evenly. Bake for 25-30 minutes.
Allow to cool for about 10 minutes, then lift out using the parchment overhang. Let cool completely on a wire rack before cutting into squares.