Baked Eggs in Potatoes

4 large baking potatoes
2 Tbs. plus 2 tsp. olive oil
2 ounces Gruyère cheese (optional), grated
2 ounces grated Parmesan cheese
2 ounces Swiss cheese, grated
1 tsp. caraway seeds
1/4 cup unsalted butter
8 scallions, trimmed and thinly sliced
1 red bell pepper, seeded and diced
2 ounces mushrooms, finely diced
8 slices prosciutto or smoked ham
8 eggs

Preheat oven to 400°F. Rub each potato with oil. Bake about 40 minutes or until potato yields to pressure. Combine grated cheeses with caraway seeds in a small bowl. Set aside. Melt butter in a large heavy nonstick skillet over medium heat. Sauté scallions, bell pepper and mushrooms. Cut cooked potatoes in half lengthwise. Scoop out most of the flesh, leaving a 1/4 inch thick shell. Stir potato flesh into cooked vegetables. Place potato shells on a baking sheet. Sprinkle 1-1/2 tsp. cheese mixture into each shell. Line each shell with 1 slice prosciutto. If necessary, fold ham to fit. Break 1 egg into each shell. Bake about 8 minutes or until eggs are barely set. Remove from oven. Turn on broiler. Sprinkle each egg-potato with remaining cheese. Top with vegetable mixture. Broil until cheese just melts or about 1 minute.