Prepare potatoes according to package, adding 1/2 teaspoon salt and 1/4 teaspoon pepper. Stir in eggs, cream cheese, and onion; fold in pimiento. Place in a lightly greased 11- x 7-inch pan.
Bake, covered, at 350° for 30 minutes. Uncover and sprinkle with cheese. Bake 10 more minutes.