Ratatouille Lasagna

extra virgin olive oil, divided

medium yellow onion, chopped

garlic, minced

medium eggplant (about 1 lb.), cut into ½" cubes

medium zucchini, cut into ½" cubes

yellow bell pepper, seeded and chopped

red bell pepper, seeded and chopped

(2) 28 ounce cans crushed tomatoes

tomato paste

sugar

bay leaf

sprigs fresh thyme or 1 teaspoon dried

leaves fresh basil, chopped, plus more for garnish

(1) 13.25 ounce box lasagna

(1) 15 ounce container ricotta cheese

grated mozzarella