Pierogi Casserole

Totally not pierogi, but close enough to fake it. Super easy although not easy on the number of dishes, but definitely worth it for some carb-y, fatty comfort food. There's no shame in it, and it's so, so good.

4-6 servings

5 potatoes, (40oz) 
½ cup milk
⅓ cup butter (2.7oz/76gr), melted (#1)
½ tsp salt 
½ tsp pepper 

2 Tbsps. (1oz/28gr) butter (#2)
(Optional: ¼ lb bacon, diced)
2 onions (12oz), chopped
9 lasagna noodles 
2 Tbsps. (1oz/28gr) butter (#3)
2 Tbsps. flour
1¼ cups milk
2 cups (8 oz) shredded Cheddar cheese
Sour cream
3 Tbsps. chopped fresh chives

1. Boil the potatoes in lightly salted water for 10-20 minutes, until fork-tender. Drain and mash with milk and ⅓ cup of butter, salt and pepper. Set aside.
2. Melt 2 Tbsps.' of butter to sauté the onion (if using, add them at the same time to sauté together), until soft and translucent.
3. Meanwhile, boil the water and cook the noodles until just al dente. They cook some more as the dish bakes.
4. Preheat oven to 350°F.
5. Make the bechamel sauce: melt the butter in a saucepan; add the flour and whisk, until the flour starts to turn golden. Stream in the milk, whisking to avoid lumps.
6. Layer the ingredients in a 9x13 baking dish in the following sequence: 
• a single layer of 3 noodles
• ½ of the mashed potatoes
• ⅓ of the cheese
• a single layer of 3 lasagna noodles
• the whole preparation of bechamel
• ½ of the mashed potatoes
• ⅓ of the cheese
• a single layer of 3 lasagna noodles
• ⅓ of the cheese
• onions (and bacon) on top. Season with salt and pepper.
7. Bake, uncovered, in the hot oven for 30 to 45 minutes, or until the cheese is melted and bubbly. Serve with sour cream and chopped fresh chives.