Radicchio is normally rather bitter, but the long version, and especially the radicchio di Treviso, has a softer taste. For a lasagna for 2p put 400 grams of radicchio(remove the hard core) in the oven on a baking sheet with a drizzle of olive oil. Bake at 180° for 15-20 mins, and turn halfway. The flavor of roasted radicchio is more intense and sweeter. Chop 1 fennel in small pieces and steam or boil until al dente.
Fry 1 chopped onion, 4 chopped garlic cloves in 1 large table spoons of butter. Add 1 large table spoon of flour and the fennel. Bake until you smell the flour has the right smell of freshly baked cookies. Add 300 ml of halfskimmed milk while stirring constantly. Add 1 teaspoon of dried basil, salt and pepper. Boil the sauce until the perfect texture (add some milk if too thick). Remove the sauce from the fire and add 100-150grams of soft gorgonzola (dolce latte).
Oil a dish for the lasagna. Start with the sauce, then the radicchio, then the lasagna sheet, and repeat. Finish with the sauce.