This can be assembled and refrigerated up to 24 hours ahead of time. Let stand 30 minutes at room temperature and bake as directed. You can substitute any sharp Italian cheese (such as Romano, provolone, or Asiago) for the Parmesan.
1 cup boiling water
3/4 cup sun-dried tomatoes, packed without oil (about 2 ounces)
3 pounds peeled baking potato, cut into 1/4-inch-thick slices
1 tablespoon butter or stick margarine
1 cup chopped onion
1/2 teaspoon dried oregano
1/4 teaspoon salt
1/4 teaspoon black pepper
1/4 cup all-purpose flour
2 1/4 cups fat-free milk
2 cups (8 ounces) grated fresh Parmesan cheese
How to Make It
Combine water and sun-dried tomatoes in a bowl; cover and let stand 30 minutes or until soft. Drain and coarsely chop; set aside.
Preheat oven to 350°.
Place the potato in a large saucepan, and cover with water; bring to a boil. Reduce heat; simmer for 15 minutes or until tender. Drain well. Arrange potato in a 13 x 9-inch baking dish coated with cooking spray.
Melt butter in pan over medium heat. Add onion; cook 3 minutes or until tender. Add sun-dried tomatoes, oregano, salt, and pepper, and cook 2 minutes. Lightly spoon flour into a dry measuring cup; level with a knife. Sprinkle tomato mixture with flour; cook 1 minute, stirring constantly. Gradually add milk, stirring with a whisk until blended. Remove from heat; add cheese, stirring until cheese melts. Pour the sauce over the potatoes, tossing gently to coat. Bake at 350° for 20 minutes or until bubbly and golden.