Brown ground turkey with the onion and garlic, adding bell pepper, carrot, or celery when the recipe calls for them. Drain excess fat and transfer the cooked mixture to the slow cooker.

Add the appropriate tomatoes, sauce, broth, beans, vegetables, grains, or seasonings for the selected recipe. Stir gently so the ingredients are evenly distributed.

For meatballs, mix the turkey gently with egg, breadcrumbs, Parmesan, garlic, parsley, and seasonings, then form 20 to 24 meatballs. Pour marinara into the slow cooker and nestle the raw meatballs into the sauce.

Cover and cook according to the recipe timing, generally 4 to 8 hours on LOW or about half as long on HIGH. Check lean turkey dishes early because they can dry out if cooked beyond the recommended time.

Add ingredients that need a shorter cooking time near the end, including rice for the stuffed pepper soup, milk for the Bolognese, quinoa toppings, and broken lasagna noodles. Follow the timing given for each recipe so grains and pasta stay tender instead of mushy.

Confirm that cooked ground turkey and meatballs reach an internal temperature of 165°F. Taste the finished dish and adjust salt, pepper, or a small splash of lemon juice or red-wine vinegar where appropriate.

Serve with the recommended toppings, pasta, tortillas, buns, or cheese. Cool leftovers promptly and store pasta or rice separately when possible for the best reheated texture.