Brush on a light amount of butter inside the casserole dish.
Take the udon out of the package in cut into big bite sizes. Boil the noodles in boiling water for 1 minute. Once the noodles are cooked, drain and place in the casserole dish.
In a frying pan, cook the bacons, mushrooms, and onions. Add in the soup seasoning, butter, and butter. Lower the heat. Slowly add in the milk while stirring, so that the sauce does not get clumped. Once the sauce thickens, the white sauce is ready. Add salt and pepper to taste.
Pour the white sauce on top of the udon and bake in the toaster oven for 10 minutes. Add shredded cheese to the dish and bake for another 10 minutes. To finish, sprinkle on parsley. Enjoy!