Heat a skillet over medium-high heat. Cook and stir sausage in the hot skillet until browned and crumbly, 5 to 7 minutes. Transfer sausage to a slow cooker.

Pour diced tomatoes, tortellini, Neufchatel cheese, spinach, and chicken broth into the slow cooker, making sure to chunk up cheese throughout the mixture.

Cover and cook on Low until tortellini has become tender, 4 to 6 hours.