In a sauté pan over medium heat, add olive oil. Once heated, add sliced andouille sausage and onions and cook until sausage is browned on both sides, about 5 minutes.
Add diced tomatoes, chicken broth, garlic powder, salt, pepper, and tortellini. Stir to combine. Bring to a simmer, cover, and reduce to medium-low heat. Cook for 7 to 8 minutes, or until tortellini are cooked through. Most of the liquid should be absorbed in this step.
Reduce heat to low. Add heavy cream, stir, and cook for 2 minutes.
Remove from heat. Add cheddar cheese, stir, and allow to rest for 5 minutes. Sauce will thicken as it rests.
Optionally, add scallions or chives as a garnish.
Andouille sausage can be substituted with your favorite type of sausage - chorizo or Italian sausage are great choices.
If your sauce looks thin, allow it to set for 5 minutes. The pasta will continually absorb liquid as it sits.