Preheat the oven to 375 degrees(F).
Pour the uncooked pasta shells into a 9x13 inch baking dish.
Sprinkle the cheddar and mozzarella cheeses over the pasta, then pour the milk, cream, and water over everything.
Sprinkle the salt, onion powder, garlic powder, paprika, mustard, and cayenne over the pasta. Stir to combine everything.
Put the cream cheese into the baking dish, and break it up a little bit with a spoon, and stir everything again as best you can. Press the pasta down evenly into the liquid.
Bake for 20 minutes. Then pull the baking dish out of the oven and stir everything together again. Then smooth it back out.
Bake for another 20 to 25 minutes or until the pasta is tender. Serve!