1 Tbs. unsalted butter
1 C chopped onion
1/2 C. chopped sun-dried tomatoes
12 oz. ham, finely chopped (2 cups)
8 oz. fontina,, Gruyere or Swiss cheese, shredded (2 cups)
2 Tbs. all-purpose flour
8 eggs
3 C. milk
1 tsp. coarse salt
1/8 tsp. pepper
1/4 C. grated Parmesan cheese
Place potatoes in large pot with enough cold water to cover. Bring to a boil over medium-high heat. Reduce heat to medium-low;simmer 15-20 minutes or until potatoes are tender when pierced with fork. Drain; cool completely.
Melt butter in medium skillet over medium heat. Cook onion 5 minutes or until golden brown and softened, stirring occasionally.
Heat oven to 350 degrees. Spray 13x9-inch glass or ceramic baking dish with cooking spray. With paring knife, remove skin from potatoes. (if preferred, can leave on) Slice potatoes 1/4 inch thick.
Layer half of the potatoes in baking dish; top with half each of the sun-dried tomatoes, onion and ham. Toss cheese with flour; sprinkle half over potatoes. Repeat with remaining potatoes, sun-dried tomatoes, onion, ham and cheese mixture.
Whisk eggs in large bowl until blended; gradually whisk in milk, salt and pepper. Pour over potatoes; sprinkle with Parmesan cheese. (Casserole can be made to this point 4 hours ahead or overnight. Add 5-10 minutes before serving.)
Bake 50-55 minutes or until browned and bubbly and knife inserted in center comes out moist but clean. (Center will set as casserole cools.) Let stand 10 minutes before serving.