Pasta with Sausage Meatballs, Peppers, and Onions

garlic cloves, minced and divided

sweet Italian sausage (or a combination of sweet and hot), casings removed

freshly grated Parmesan cheese, plus more for serving

fresh flat-leaf parsley, minced

freshly ground black pepper, plus more to taste

olive oil, divided

onion, sliced

red bell peppers (or 1 red and 1 yellow), seeded and sliced

Salt,

dry white wine

dry pasta, such as cavatappi

prepared pesto, or to taste