The vegetables here are roasted in the oven to bring out their flavor instead of cooked for a long time in a crock pot or on the stove, like some other ratatouille recipes. This recipe is from Ellie Krieger's first cookbook, The Food You Crave.
For the crust: Combine cornmeal, flour, and salt in the bowl of a food processor. Pulse to incorporate. Add butter and oil and pulse about 20 times, until mixture resembles small pebbles. You can also do this by hand, using a pastry cutter to cut the butter in, or the two-knife method.
Add water and pulse (or stir with a wooden spoon) until mixture forms a loose dough.
Remove dough from processor (or bowl) and press into the bottom and about 1/8-inch up the sides of a 9-inch tart pan with a detachable rim (or a springform pan).
Press aluminum foil into the bottom and sides of the pan on top of the dough and weigh down with uncooked rice, raw beans, or pie weights.
Place tart pan on a baking sheet and bake for 10 minutes.
Remove from the oven and remove rice (or beans or pie weights) and foil. Return to oven and bake for an additional 5 minutes, or until no longer shiny and wet. Remove from oven and let cool.
Increase the oven to 400 degrees F.
For the filling: Heat 1 teaspoon of olive oil in a nonstick pan over medium heat; saute shallots until soft, about 5 to 6 minutes.
Line 2 baking trays with aluminum foil, and spray with cooking spray.
Arrange the eggplant, zucchini, and tomato slices on the trays in a single layer and brush with the remaining olive oil. Season with salt and pepper, and roast the vegetables until soft but not browned, about 15 minutes.
Remove the vegetables from oven and cool.
Lower the oven temperature to 350 degrees F. Lay the eggplant slices in 2 layers on the bottom of tart; cover with 1/3 of the mozzarella cheese and some of the shredded basil.
Add the zucchini and shallots, top with another 1/3 of the mozzarella and basil, then the tomatoes.
Top with rest of the mozzarella cheese and the Parmesan.
Bake for 25 to 30 minutes, or until cheese is melted and vegetables have further wilted.
Remove from oven, let cool for 5 minutes, and cut into 8 slices.