Preheat oven to 375°. Place potatoes in a large saucepan; add water to cover. Bring to a boil. Reduce heat; simmer, covered, 8-10 minutes or until crisp-tender. Meanwhile, in a large skillet, heat butter over medium-high heat. Add onion; cook and stir 6-8 minutes or until tender. Add garlic; cook and stir 1 minute. Stir in flour until blended; gradually whisk in milk. Bring to a boil, stirring constantly; cook and stir 1-2 minutes or until thickened. Stir in Alfredo sauce and seasonings; heat through., Drain potatoes; transfer to a greased 13x9-in. baking dish. Layer with ham, cheese and sauce. In a small bowl, combine bread crumbs and butter. Sprinkle over top. Bake, uncovered, 18-22 minutes or until topping is golden brown and cheese is melted. Let stand 5 minutes before serving. To Make Ahead: Can be made a day in advance. Prepare recipe as directed, layering ham, cheese and sauce in baking dish. Cover and refrigerate overnight. Remove from the refrigerator 30 minutes before baking. Prepare crumb topping; sprinkle over top. Bake as directed.