Preheat the oven to 350. Grease an 8 x 8 baking dish.
Stir together the wet ingredients. Add the dry ingredients. Spread in the greased baking pan. Sprinkle on the chocolate chips, if using. Bake for 25 minutes until no longer jiggly in the middle. Cool to room temperature.
Coffee Buttercream:
Mix the half and half and instant coffee granules in a medium bowl until dissolved. Add the butter and cream cheese and beat until fluffy. Add the powdered sweetener and vanilla and beat again until fluffy.
Caramel Sauce:
Combine the sweetener, cream, and butter in a medium saucepan. Cook over medium, stirring frequently, until deep golden brown and thickened. Depending on the heat of your stovetop this can take 10-15 minutes. Watch it carefully. Cool for 5 minutes before assembly.
Assembly:
Gently spread the buttercream on the cooled brownies. Pour the caramel sauce on top of the buttercream. Swirl with a butter knife making zig-zag lines one way and then the other. Enjoy!