Place potatoes in a lightly greased roasting pan. Bake at 400° for 50 minutes or just until tender. Let cool. Cut potatoes in half. Using a small spoon, scoop out most of pulp from each potato half. Set shells aside.
Combine potato pulp, Gruyère cheese, and next 6 ingredients; stir mixture well. Spoon mixture into potato shells. (You can make the potato bites ahead up to this point and store them in the refrigerator overnight.)
Place potatoes on a rack in a roasting pan. Broil 5 1/2" from heat (with electric oven door partially opened) 4 to 5 minutes or until golden. Garnish, if desired.