Easy Pierogi Casserole

Gather the ingredients. The Spruce / Qi Ai Soak noodles in warm water for 30 minutes, making sure they don't stick to each other. The Spruce / Qi Ai Meanwhile, in a medium pot, boil potatoes in salted water until tender. The Spruce / Qi Ai While potatoes are cooking, mix together cottage cheese, egg, and 1/4 teaspoon onion salt, and set aside. The Spruce / Qi Ai When potatoes are tender, drain, mash them and stir in Cheddar cheese, 1/4 teaspoon regular salt, remaining 1/4 teaspoon onion salt and pepper, and set aside. The Spruce / Qi Ai Heat oven to 350 degrees. In a 9-inch-by-13-inch pan that has been lightly coated with nonstick spray, place 3 drained noodles horizontally. The Spruce / Qi Ai Spread cottage cheese over the first layer of noodles. Lay down another 3 noodles. The Spruce / Qi Ai Spread mashed potato mixture evenly over the second layer of noodles. Cover with another 3 noodles. The Spruce / Qi Ai Spread 1/2 cup caramelized onions evenly over the third noodle layer. The Spruce / Qi Ai Cover with remaining 3 noodles. Mix remaining 1/2 cup onions with bread crumbs and spread over the top of the last noodle layer. The Spruce / Qi Ai Cover casserole dish with foil and place on a pan to catch drips. Bake for 30 minutes or until the dish is bubbly. The Spruce / Qi Ai Uncover and bake 5 minutes more. Let stand 10 minutes before cutting into squares as for lasagna. Serve with sour cream and chopped dill, if desired. The Spruce / Qi Ai