1) To make bechamel: Melt butter in small saucepan over low heat. Add flour; cook for 5 minutes, stirring constantly. Whisk in cream slowly, until mixture thickens. Strain into large bowl; cool. Mix cooled bechamel with 5 cups tomato sauce, Parmigiano-Reggiano cheese and Romano cheese.
2) Medium-dice red pepper, yellow pepper, zucchini, summer squash, white onion and red onion; toss with olive oil and salt and pepper. Roast at 350ºF for 20 minutes until tender. Add spinach. Cool vegetables.
3) Cook lasagna sheets in large pot of boiling salted water for 8-10 minutes, or until al dente. Strain; rinse under cold water. Pat dry with kitchen towel; drizzle with olive oil.
4) In greased 9×13-inch baking dish, layer lasagna as follows: tomato mixture, lasagna sheets, vegetables, mozzarella, tomato mixture. Repeat at least four times until reach top of baking pan. Add remaining cup tomato sauce; top with mozzarella.
5) Cover with aluminum foil; bake at 350ºF for 50 minutes. Remove foil; continue baking for 20 minutes, untilcrust is golden. Remove from oven; rest about 20 minutes before slicing.