Heat olive oil in a large pot on medium heat. Add onion and cook for 3 minutes or until tender. Add in red pepper and garlic and cook 2 minutes more.
Add diced tomatoes, spaghetti sauce, and seasonings. Bring to a boil and then reduce to low heat and simmer for 1 hour or until sauce thickens.
Add cooked chicken and simmer for 5 minutes more. Serve on zucchini noodles or your favorite low carb pasta.
Notes
Use store-bought rotisserie chicken for this recipe and freeze the rest for soups and future meals.Or, make this pasta sauce without chicken for a low-carb, classic vegetarian marinara.