Steps
1. In a large skillet, melt the butter over medium heat.
2. Add the sliced mushrooms and chopped onions to the skillet. Sauté until the mushrooms have softened and the onions are translucent.
3. Stir in the shredded cheese until melted and smooth.
4. Add the cooked pasta to the skillet and toss until well coated with the cheese sauce.
5. Season with salt and pepper to taste.
6. Serve hot and enjoy!