Boil the Potatoes: Peel and cut large potatoes into chunks, then place them in a pot of salted water. Boil for about 25 minutes until tender, mash with garlic, sour cream, butter, milk, and cream.

Cook the Bacon and Onions: In a skillet, cook bacon over medium heat until golden. Remove and drain. Sauté onions in bacon fat until caramelized, about 10-15 minutes.

Prepare the Lasagna Noodles: Boil noodles in salted water for 5 minutes less than package instructions, drain, and toss lightly in olive oil.

Layer the Ingredients: In a greased baking dish, layer the potato filling, lasagna noodles, caramelized onions, crispy bacon, and cheddar cheese. Repeat layers 4 to 5 times, finishing with cheese and reserved bacon.

Bake the Lasagna: Preheat oven to 350°F (175°C). Cover with foil and bake for 30 minutes. Remove foil during the last 10 minutes to melt and brown the cheese.

Cool and Serve: Let lasagna cool for 10 minutes before slicing. Garnish with fresh chopped scallions.