Start out by heating the oil in a large, deep skillet with a tight fitting lid over medium heat. Add the onion and cook about 3-4 minutes. Then add the ground beef and cook until browned through, breaking it up as you go. Drain out any excess fat, if needed. Then add the pasta and milk to the skillet

Using a tbsp. of the water you have measured, mix it and the cornstarch together in a small separate bowl to form a slurry. Add the rest of the water to the skillet along with the seasonings and the cornstarch slurry. Stir it all together and wait for it to come to a boil.

Once it reaches a boil, reduce the heat to low and cover with the lid. Allow to simmer, stirring occasionally, for about 10-12 minutes, or until pasta is al dente. Then remove the skillet from the heat and stir in the cheese until it's incorporated in. Place the lid back on and let it sit for 5 or so minutes before serving.