Preheat your oven to 180 degrees C. Line the bottom and sides of an 8 inch (20 cm) square baking pan with foil. Butter the foil.

Melt the chocolate and butter in a large stainless steel bowl placed over a saucepan of simmering water. Remove from heat and stir in the cocoa powder and sugar.

Next, whisk in the vanilla extract. Then, whisk in the eggs, one at a time, beating well after each addition. Finally, stir in the flour, salt, and chocolate chips.

Pour into the prepared pan, smoothing the top with the back of a spoon or offset spatula. Bake for about 25 minutes or until a toothpick inserted in the center comes out with a few moist crumbs clinging to it. Remove from oven and let cool on a wire rack.