Soak bread in milk, squeeze. Chop the peeled onion and garlic. Peel carrots and celery, chop coarsely. Chop nuts. Wash mushrooms, finely chop.
In a skillet, melt 1 tbsp. l. oil, sauté the onion and garlic until translucent. Add mushrooms, continue frying until the water evaporates. Remove from fire.
Peel the potatoes, boil them, drain the water, salt, pepper, mash, adding butter and warmed milk. Pass the turkey fillet through a meat grinder. Put the minced meat in a bowl, add the soaked bread. Salt, pepper to taste, mix well. Put the minced meat in a pan with mushrooms and fry, stirring, for 10-15 minutes. Cool, beat in 2 eggs, add breadcrumbs, mix again.
Grease a rectangular baking dish with oil. Preheat the oven to 200ºС. Put a layer of mashed potatoes in a mold, on it - a thin layer of minced meat. Put chopped carrots and celery on minced meat, sprinkle with chopped nuts. Cover with the remaining minced meat, then a layer of mashed potatoes. Drizzle with melted butter and bake in the oven for 35-40 minutes.
Prepare the sauce: fry the chopped onion in butter and punch in a blender with the rest of the ingredients. Rub through a sieve, warm. Cut the finished casserole into portions. Separately serve cranberry sauce.