In a skillet, cook bacon until crisp; remove to paper towels to drain.
In a mixing bowl, beat egg yolks until light, about 2 minutes.
Beat in onion, mustard and pepper.
Place potatoes in a bowl; fold in egg yolk mixture.
Set aside 2 Tbsp bacon. Fold cheese, parsley and remaining bacon into potatoes.
In a small mixing bowl, beat egg whites until stiff; fold into potato mixture.
Transfer to a greased 1-qt baking dish. Sprinkle with reserved bacon. Bake, uncovered at 325 for 45-50 minutes or until set and edges are golden brown. Serve immediately.
