Pasta: Cook lasagna noodles, according to package directions, until el dente; drain & dry well on a clean tea towel or paper towels and set aside.
Veggies: Heat oil in a large pan over medium heat, saute onions& peppers until limp (about 10 minutes); stir in thyme, remove from heat& set aside.
Bechamel Sauce: Melt butter in a heavy saucepan & stir in flour; Gradually whisk in milk, broth, wine, salt& pepper.
Cook over medium heat, stirring constantly, until smooth & thickened; remove from heat, add nutmeg & 1/2 cup of the grated Parmesan, stir & set aside.
Assembly: Grease a 9 x 9 inch baking dish& assemble in this order: layer of noodles;layer 1/2 of the chopped tomatoes; layer of noodles;layer 1/2 of the pepper mixture; layer 1/2 of the Mozzarella; layer of noodles; layer rest of the diced tomatoes; layer of noodles; the rest of the pepper mixture; the rest of the mozzarella.
Spread the Bechamel sauce over the top& sprinkle with the remaining Parmesan.
Bake, uncovered, at 375F for 45 minutes; tent with foil & let stand for 15 minutes before cutting.