Ingredients
5 tablespoons olive oil, divided
2 medium onions, thinly sliced
1 medium garlic clove, minced
1 1/4 pounds small or medium, ripe tomatoes (cored and cut into 1/4-inch slices)
3/4 pound (2 small) zucchini, cut into 1/4-inch slices
3/4 pound (2 small) yellow summer squash, cut into 1/4-inch slices
1/4 cup chopped fresh thyme, divided
1 teaspoon salt, divided
1 1/4 cups grated Parmesan cheese, divided
freshly ground black pepper, to taste