To start, remove the sausage meat from the casings in small clumps so that they look like little meatballs.
Heat the olive oil in a large saucepan, add the sausage clumps and brown the sausage until there is no pink left drain the fat from the pan. Transfer to paper towels and set aside.
Add more oil to the pan if necessary. Add the chopped onion and the and cook until they are soft and the sausage balls are a golden brown. Add the garlic and fry for another minute.
Add the sausage meat, tomatoes, herbs, a pinch of cayenne pepper, and if using, crumble the stock into the mixture. Bring to a boil.
As soon as the sauce comes to a boil, reduce the heat to low, and simmer covered over medium heat for about 20 minutes. Add salt and pepper to taste before serving.
When the sauce has about 10 minutes to go, cook the pasta until just underdone and reserve some water before draining. Drain and add to the sauce to finish cooking (if the sauce has gotten too thick, add some of the reserved pasta water to help loosen it). Serve hot.
Slow Cooker Instructions
Follow the stovetop instructions through step 5. Then transfer to a slow cooker, cover, and cook on low for 8 hours or on high for 3 to 4 hours, stirring occasionally.
Notes
For an extra depth of flavor, allow the onions to brown in the pan and scrape any crispy bits from the bottom of the pan when you add the tomatoes.
Stir often to keep the sauce from sticking to the bottom of the pan.
Use ready-made tomato sauce for an even speedier dish.