In a large dutch oven or sauté pan (oven-safe if you have it), add the olive oil and bring over medium heat. Add the onions and sausage to the pan and cook for 5-6 minutes until sausage is browned and onions are tender. Add the garlic and stir. Continue to cook for another 30 seconds until fragrant.

Add the broth, Ro-Tel, half and half, salt and pepper and mix together. Add the uncooked pasta and stir together until the liquid covers the pasta. Cover the skillet and bring the mixture to a boil. Reduce the heat to medium-low and keep covered. Simmer for 15 minutes or until the pasta is cooked.

Set your oven to broil and make sure one of your oven racks is in the top 1/3 of the oven. Remove the pan from the heat and mix in half of the shredded cheese. If your pot is oven-safe, you may continue to use it in the following steps. If it isn’t or you aren’t sure, transfer the pasta into a baking dish. I used a 7x11 dish but you can certainly use a 9x13.

Sprinkle the remaining shredded cheese over the top of the pasta and follow it with the sliced scallions. Place the dish in the top 1/3 of the oven and broil for a few minutes until the cheese is melted and beginning to brown (keep checking because broiling can happen really fast!).