Preheat oven to 350°.
Place potatoes in a large saucepan; cover with water. Bring to a boil. Reduce heat; simmer 5 minutes or until potatoes are almost tender. Drain. Sprinkle potatoes evenly with 1/4 teaspoon salt; set aside and keep warm.
Heat a medium saucepan coated with cooking spray over medium heat. Add shallots; cook 2 minutes or until tender, stirring frequently. Lightly spoon flour into a dry measuring cup; level with a knife. Sprinkle flour over shallots. Gradually add 1/2 cup milk, stirring with a whisk until well blended. Gradually add remaining 1 1/2 cups milk, stirring with a whisk. Cook over medium heat 9 minutes or until thick, stirring frequently. Remove from heat; stir in 3/4 teaspoon salt, Asiago, chives, pepper, and bacon.
Arrange half of potato slices in an 8-inch square baking dish coated with cooking spray. Pour half of cheese sauce over potato slices. Top with remaining potato slices and cheese sauce; sprinkle with Parmesan. Bake at 350° for 35 minutes or until cheese is bubbly and lightly browned.