Roasting the radicchio mellows its slightly bitter flavor; balsamic vinegar adds a touch of sweetness. You can use either of the popular varieties of radicchio -- round Verona or slender Treviso -- in this recipe, since they both yield delicious results. Serve the radicchio wedges alongside the pasta.
First of all, you have to LIKE radicchio in all its bitterness. Roasted in the oven with olive oil, salt and pepper somewhat tames the beast but it’s still bitter. Balsamic vinegar added near the end of the roasting time topped by Parmesan that is well melted is the perfect foil for this vegetable. A sweeter balsamic reduction is also good. If the cheese melts on to the sheet pan, all the better. Just fold it back over the radicchio. Delish