Preheat oven to 350° F. Line an 8-inch square pan with parchment paper. Set aside.
In a medium bowl, whisk together flour blend, salt, cinnamon, and cayenne pepper. Set aside.
In a large heatproof bowl set over a pot of simmering water, combine chopped chocolate, butter or substitute and vanilla extract. Stir frequently until melted.
Remove from heat and let the melted chocolate mixture cool slightly.
Whisk in sugar, then eggs and egg yolk. Fold in flour mixture. Transfer batter to prepared pan and smooth top with a spatula.
Bake for 22-24 minutes or until a toothpick inserted in center comes out with a few moist crumbs. Sprinkle chocolate chips over brownies and return to oven for 1-2 minutes until chocolate chips have melted. Remove from oven and spread over top until smooth.
Refrigerate until chocolate is firm, then cut into 9 squares. Serve at room temperature.