Heat medium sauce pan over medium-high heat and add 1 Tbsp olive oil. Add sausage and cook until well browned, breaking sausage up into small pieces while cooking, about 8 minutes. Remove sausage from pan and set aside.

In a separate large pot, start bringing 3 quarts of water to a boil. Once water is boiling, salt generously (at least 1 Tbsp). Do not add pasta yet.

Turn heat on sauce pan to medium and add 1 Tbsp olive oil. Add onion and cook until soft, about 5 minutes. Add garlic, then cook 30 seconds until fragrant.

Push onions and garlic to sides of pan, then add tomato paste to center and cook until slightly browned, about 1 minute. Stir tomato paste into onions and garlic, then stir in Italian seasoning.

Deglaze with white wine, scraping brown bits from bottom of pan. Cook until wine has reduced by half, 2-3 minutes.

Return sausage to pan. Add diced tomatoes, including the liquid from the can, passata, and a bay leaf, stir to combine everything, bring to a simmer, then reduce heat to medium-low and allow sauce to simmer while pasta cooks.

Add Gemelli pasta to salted boiling water and cook for 1 minute less than packaging recommends. Once pasta is just shy of al dente, transfer directly from water to sauce pan, do not strain. Add about ¼ cup pasta cooking water to sauce pan, stir everything to combine, then bring to a simmer and let pasta finish cooking in sauce, about 1-2 minutes.

Remove bay leaf. Taste for seasoning. Add salt and pepper if needed. Top with grated parmesan cheese and chopped parsley, then serve.