In a 1 1 1/2-quart casserole stir together the ham and the drained mushrooms.
In a mixing bowl stir together the eggs, skim milk, grated Parmesan cheese, dried parsley flakes, onion powder, and pepper.
Pour the egg mixture evenly over the ham mixture in the casserole.
Micro-cook, uncovered, on 100% power (HIGH) for 4 to 6 minutes or till the egg mixture is almost set, pushing cooked portions to center of the casserole several times during cooking.
Sprinkle with the shredded mozzarella cheese.
Let stand for 5 minutes