Start by cutting the zucchini into thin slices. Warm some olive oil in a pan and add a cracked clove of garlic (so that you can take it out once the zucchini is cooked). When the garlic has browned a little add the zucchini slices, cover the pan and stew them and add salt. Add water if needed.
Cut the radicchio into thin stripes and follow the same procedure as to stew the zucchini, adding together with the garlic two leaves of sage. Do not let burn, the radicchio takes a short time to stew.
Meanwhile (I usually do this when starting stewing the zucchini), peel the potatoes and boil them in salt water until they're tender. Strain and smash them - make sure there are no big lumps.
Add the stewed zucchini and chicory to the mashed potatoes, together with some olive oil, black pepper and some salt if needed, then mix all the ingredients together.
Cover the bottom of a baking pan with oil and sprinkle cornmeal on it. Pour the mixture in the baking pan and level the surface, pour some oil on it.
Put the baking pan in pre-heated oven at about 430°F and cook for about 20 minutes.
Serve warm - wait some minutes after taking it out of the oven.