Preheat oven to 375°F. Cook pasta until tender. Drain and cool.
In a skillet over medium high heat brown ground beef, season with salt and pepper and drain well.
Turn down to low heat and add cream cheese and use a meat masher or sturdy spoon to mix well.
Stir in parmesan cheese and half of cheddar cheese until lightly melted. Set skillet off of the heat.
Stuff shells and arrange in a single layer in a 9 x 13" or larger baking dish. An additional smaller dish may also be needed.
Spread sauce over pasta and cover with foil. Bake for 40-45 minutes until shells are warmed through.
Uncover and sprinkle remaining cheese on top in an even layer. Return to over for about 10 minutes until cheese is melted and lightly browned. Serve warm and enjoy!