In a large skillet, heat the olive oil (1 tablespoon) until it shimmers. Add Italian sausage (1 pound), onion, and garlic, and cook over medium heat until sausage is cooked through. Drain off excess fat. Pour the drained sausage mixture into a large crock pot.
Add salt (1 teaspoon), pepper (1/2 teaspoon), oregano (2 teaspoons), basil (2 teaspoons), rosemary (1 teaspoon), sugar (1/4 teaspoon), 2 jars of marinara sauce, red wine (1 cup), and water (2 1/2 cups) to the crockpot and stir together. Cook on high for 3-4 hours or low for 6-8 hours.
Cover and turn the crockpot on high for the last hour add spaghetti (1 pound). Break noodles, as needed to fit into crockpot. Stir the noodles well into the sauce so they're coated with the sauce. Check pasta after 45 minutes to see if the spaghetti is done. Add more water as needed to loosen the sauce.
Notes
Managing the Moisture- If the sauce is too tight, simply add a little broth or water and stir. However, decreasing moisture in a runny sauce can be a little more tricky. You can prop open the top with a wooden spoon or remove it entirely.
You can also drape a clean kitchen towel across the pot under the lid. Beware you’ll probably stain your towel, but it’s quite effective at soaking up excess moisture!
Cooking Time – Look, every crock pot is different. Period. There’s no magic cooking time I can tell you. What’s in the recipe is a general guideline: 3-4 hours on high or 6-8 hours on low. The exact cooking time may (will) vary based on your cooker.