Preheat oven to 450 degrees F (230 degrees C).
Into a mixing bowl, add Elbow Macaroni (1 pound), Cream Cheese (8 ounce) and Unsalted Butter (6 tablespoon). Mix well.
Add 2% Reduced Fat Milk (3/4 cup) and mix to combine.
Add Sour Cream (1 cup), Ground Black Pepper (1 1/2 teaspoon), and Salt (3/4 teaspoon). Mix to combine.
Add Cheese (4 cup). Stir until well-combined.
Add Egg (3). Mix well.
Transfer mixture into a greased 10-inch cast iron skillet.
Sprinkle remaining Cheese (1 cup) over top.
Place skillet on a sheet pan in case cheese bubbles over. Cover skillet with greased sheet of aluminum foil. Bake for 45 minutes.
Remove the foil and bake for another 20 minutes or until cheese is golden brown.
Let dish sit for 20 minutes to cool.