Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.

In a large mixing bowl, cream together the unsalted butter and granulated sugar until light and fluffy, about 3-5 minutes.

Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

Sift in the all-purpose flour, cocoa powder, and salt, and gently fold until just combined.

Fold in the semi-sweet chocolate chips until evenly distributed.

Pour the batter into the prepared baking pan and spread evenly.

Bake for 25-30 minutes or until a toothpick comes out with a few moist crumbs.

Allow to cool in the pan for 10-15 minutes before slicing into squares and serving.