Steps:

• Bake potatoes at 450° for 1 hour or until tender. Allow to cool to touch.
• Cut potatoes in half lengthwise; scoop out pulp, and place in a bowl, leaving shells intact. Set pulp and shells aside.
• Melt butter in a small skillet over medium-high heat; add chopped ham, diced onion, and minced garlic, and sauté until onion is tender.
• Mash potato pulp; stir in ham mixture, sour cream, salt, and pepper. Stuff shells with potato mixture; sprinkle evenly with Parmesan cheese. Place in a 13- x 9-inch pan or casserole dish.
• Bake at 350° for 25 to 30 minutes. Garnish, if desired.

Steps:

• Place potatoes into a large pot and cover with salted water; bring to a boil. Reduce heat to medium-low and simmer until tender, about 20 minutes. Drain.
• Preheat oven to 350 degrees F (175 degrees C).
• Grease a 1 1/2-quart baking dish.
• Melt 3 tablespoons butter in a skillet over medium heat. Stir in the ham and onion; cook and stir until the onion has softened and turned translucent, about 5 minutes.
• Stir potatoes into ham mixture; transfer to the prepared baking dish.
• Melt 1/4 cup butter in a saucepan over medium heat. Stir flour into melted butter until smooth.
• Gradually whisk milk into flour mixture; season with salt and black pepper. Continue cooking and stirring until thickened, about 2 minutes.
• Reduce heat to medium-low and stir Cheddar cheese into the white sauce until melted.
• Pour sauce over ham and potatoes.
• Sprinkle bread crumbs atop casserole.
• Bake in the preheated oven until sauce is bubbly and browned, 25 to 30 minutes.