3 root lasagna with Recipes

cubed peeled butternut squash (about 2 1/2 lb), cubed peeled sweet potato (about 1 lb), coarsely chopped onion, divided, olive oil, low-fat milk, ground nutmeg, ground cinnamon, bay leaf, all-purpose flour (about 1/3 cup), salt, freshly ground black pepper, grated parmigiano-reggiano cheese, packaged no-boil lasagna noodles, shredded part-skim mozzarella cheese

celery root , about, fresh lemon juice, sea salt, tomato sauce (preferably homemade ), heavy cream, butter , for preparing the gratin dish, freshly grated parmigiano-reggiano cheese