In a large pot, bring salted water to a rolling boil. Add 12 ounces of penne or rotini pasta and cook according to package instructions until al dente, typically about 8-10 minutes. Drain the pasta and set aside.

In a large skillet, heat 1 tablespoon of olive oil over medium heat. Add the diced onion and minced garlic, sautéing for about 3 minutes until the onions are translucent.

Add 1 pound of ground beef to the skillet, breaking it apart. Cook for 6-8 minutes until browned. Drain any excess fat.

Stir in the undrained 10-ounce can of Rotel tomatoes with green chilies and the 10.5-ounce can of condensed cream of mushroom soup into the skillet. Mix thoroughly over medium heat for about 2-3 minutes.

Pour in 1 cup of heavy cream, stirring gently. Bring to a simmer and allow it to thicken for about 5 minutes.

Reduce heat to low, then stir in 2 cups of shredded cheddar cheese until melted and fully combined, about 2-3 minutes.

Season with salt and pepper to taste, adjusting as needed.

Add the drained pasta back into the skillet, gently tossing to ensure even coating with the creamy sauce. Allow to mingle for 1-2 minutes on low heat.

Serve hot, garnishing with chopped green onions if desired.