Prepare the ingredients: rinse, dry and chop 3/4 cup Onions, peppers (3/4 cup Red Bell Pepper, 3/4 cup Green Bell Pepper), and 12 ounces Mushrooms.
Heat olive oil in a heavy 10 to 12 inch skillet over medium-high heat. Once the skillet is hot, add the bell peppers and mushrooms: cook until they start to soften and remove from heat and set aside.
Add 1 pound Ground Beef; to the same skillet and cook for a few minutes. Add the onions and continue to cook over medium heat until the beef is almost cooked through and the onions begin to soften.
Add 8 ounces Dry Pasta to the skillet with the ground beef and onions along with 2 1/2 cups Water. Reduce the heat to low, cover and cook for 10 minutes.
Remove the cover and stir in the cooked peppers, mushrooms and 4 ounces of cheese; cover again and cook for 5 to 7 minutes longer - until the pasta is cooked through and the cheese has melted.
Remove from the heat and add the remainng cheese to the top of the pasta and serve.