Fill a large pot with lightly salted water. Bring to a boil, add lasagna noodles 3 or 4 at a time, and cook for about 10 minutes until firm to bite. Drain and lay flat on waxed paper or foil.

Preheat the oven to 350°F (175°C). Grease a 9x11-inch baking dish.

Place potatoes in a large pot, cover with water, and boil over high heat. Reduce heat, cover, and simmer until tender (about 20 minutes). Mash potatoes with milk, butter, onion salt, salt, and pepper. Stir in Cheddar cheese and set aside to cool.

In a large skillet, cook bacon over medium-high heat for about 10 minutes until crispy. Add chopped onion to the bacon fat and cook for 8 minutes until translucent. Break bacon into pieces and set aside with onions.

In a bowl, mix cottage cheese, egg, and onion salt.

Layer 3 lasagna noodles onto the prepared baking dish and spread the cottage cheese mixture evenly. Repeat with noodles and potato mixture. Add the last layer of noodles topped with bacon and onion mixture.