In another bowl, stir together the ricotta, parsley, salt and pepper. Set aside.
Spread a thin layer of the sauce on the bottom of the slow-cooker insert. Cover the sauce with a single layer of uncooked lasagna noodles (about 3), breaking the noodles as needed to fit. Spread about ⅓ cup of the ricotta mixture over the noodles. Top with about 2 cups of the sauce, then sprinkle with about 1 cup of the mozzarella and ¼ cup of the Parmigiano-Reggiano. Repeat the layering 4 more times, starting with the noodles.
Transfer the insert to the slow-cooker base, cover and cook on low according to the manufacturer’s instructions until the noodles are tender and cooked through, about 4 hours.
Position a rack in the center of an oven and preheat to broil.
Transfer the slow-cooker insert to the oven and broil until the cheese is bubbly and golden brown, 6 to 8 minutes. Let the lasagna rest for 20 minutes before serving. Garnish with basil and serve immediately. Serves 12.
Recipe by In Good Taste at http://ingoodtaste.kitchen/classic-slow-cooker-lasagna/