Line an 8 ½ x 4 ½ loaf pan with aluminum foil and lightly spray with cooking spray; preheat oven to 350F.
Place the chocolate chips, cocoa, and butter in a small bowl. Microwave mixture for 30 – 60 seconds until butter and chocolate is melted. Stir with a spoon until well combined and smooth; set aside.
In a large bowl whisk together the sugar, egg, and egg yolk, salt, and vanilla. Using a spoon mix in the flour until just combined.
Pour and spread batter evenly into the loaf pan and bake for 24 – 30 minutes until a toothpick inserted comes out clean.
Cool on a wire rack, remove, and cut into desired size bars; enjoy