Line or spray an 8x8 pan. Set aside. Preheat the oven to 350℉.
In a microwave safe bowl, add the chocolate and butter. Heat in the microwave in 30 second increments until fully melted, stirring in between each time. Stir in the vanilla extract.
While the chocolate mixture warms, add the eggs and sugar to the bowl of a stand mixer or large mixing bowl. Using the whisk attachment, whisk at medium-high speed for about 3 minutes until the batter is pale and ribbony.
Gently whisk in the chocolate mixture until fully incorporated. Then add in the flour, cocoa powder and salt. Using a spatula, gently fold together until almost combined.
Add in the chocolate chips and gently fold the batter until just combined. Pour the batter into your lined pan and bake for 24-26 minutes or until a toothpick inserted about 2/3 of the way to the centre comes out with moist crumbs.
Let fully cool before slicing and serving. Store in an airtight container for up to 3 days and enjoy!