Veggie Lover's Lasagna

medium/large zucchini (about 6 cups when cut)

olive oil, for sauteing

red bell pepper, cut into 1 -inch thin strips

small red onion, thinly sliced

small yellow onion, thinly sliced

garlic

salt and pepper

fresh baby spinach

all-purpose flour

grated Parmesan cheese, plus more for serving

fresh chopped basil

sprigs of fresh thyme, leaves removed

butter, for greasing the pan

fresh or no-boil lasagna noodles

jar (24 ounce) good tomato sauce (like Newman's Bombolina Sauce) or 3 cups homemade

farmer's cheese or ricotta

mozzarella cheese, shredded