I am not sure if it is even possible or not. I baked a almond and walnut chocolate brownie. While I was preparing the mixture I added extra cocoa powder, I though it will give the brownie a perfect chocolate color. This resulted in bit bitter brownie. The brownie is perfectly baked. I have never ever baked some thing so perfect and consistent like this brownie. Can I some how enhance sweetness of this brownie?
You could thin a little syrup or honey with water and brush it on the top of the brownies so that it soaks in a sweetens them a little. Try it on one first.
You could always frost the brownies, or you could also sprinkle powdered sugar with a sieve over the top to add a little extra sweetness.
Serve it with whipped cream or ice cream.
Next time, I imagine you'd have to increase the amount of sugar you use.
I would crumble it all up on a mixing bowl then add some honey or goldrn syrup. I would the mix it. Then I mould them back then freeze them.
Obviously, (as mentioned before), you could add a little bit more sugar, or you could add instant cocoa which is essentially cocoa powder with a bit of dried milk and sugar added. This would work, though the full flavour of the cocoa may disappear a bit.
Another way would be to slice the brownie down to very thin slices first, and then frost it as suggested by @Katherine Pitta. The combination of bitterness and sweetness will make it a very nice companion with tea or coffee.
If it were me, I would dump the idea that these were eat-alone brownies, and see what else could be done with them. That bitter chocolate makes me think of Mexico. How about this: Oaxacan turtle sundaes, with vanilla ice cream, your brownies, caramel sauce, and ancho-dusted pecans (ancho is a dark red pepper with a fair amount of heat. Ground ancho can be found many places with a decent spice selection or Mexican grocery). For extra points, sub cajeta (caramelized goats milk) for the caramel sauce
U could always crumble the brownies and add frosting, and make cake pops or “brownie pops” it’s super easy crumble the brownie mix in frosting the mold into a ball, poke a stick into it and dip into any coating (candy melts, icing, even frosting) add sprinkles on top for more sweetness, freeze and enjoy! 😉😋