Preheat oven to 350 F (175 C). In a large saucepan over medium heat, saute the onions and garlic in 2 tbsp of olive oil until soft, about 5 minutes. Add the bouillon cubes and tomatoes. Simmer, stirring frequently for 30 minutes. Remove from heat, stir in basil and season with salt and pepper. In a large skillet, heat the remaining olive oil over medium heat, add the red pepper and leek, and cook until soft, about 6 minutes. Add the mushrooms, zucchini, and carrot and cook until soft, about 5 minutes. Season with salt and pepper. Lightly oil a 9x13-inch (25x35 cm) baking pan. Spread about 1/2 cup of sauce on the bottom of the man, and lay 4 lasagna sheets over it. Sprinkle 1/3 of the vegetable mixture, followed by about 1 cup of sauce. Top with 1/4 cup of mozzarella and 3 tbsp of Parmesan. Repeat, spreading the top layer with the remaining sauce and cheese. Lightly cover with foil and bake for 40 minutes. Serves 8-10.