Potato casserole as in kindergarten

First of all, wash and boil the meat in salted water. In another saucepan, boil the potatoes, let them boil well.
Put out the onion with oil and 1 tbsp.l of water. If the dish is prepared for adults, you can also simply fry the onion until golden brown.
Scroll the boiled meat with onions through a meat grinder twice and mix well. We put it in a saucepan and add a little water. The minced meat should be viscous, not crumbly. Simmer under the lid until the onion softens.
Boil the milk
Drain the finished potatoes, leaving an approximate 100-150 ml of broth. Stretch. Add hot milk and mash and mix well again.
Add a raw egg to the mashed potatoes and stir thoroughly.
Grease the mold with vegetable oil and sprinkle with breadcrumbs. Take the form with high sides, and keep in mind that during cooking the casserole will rise.
Put half of the potatoes in the mold, lightly press, followed by minced meat, and cover with the remaining mashed potatoes. Once again, we thoroughly press down.
Grease the top of the casserole with sour cream and sprinkle with breadcrumbs.
Bake in the oven at 180 degrees for 45-60 minutes.
At this time we are preparing gravy.
We take 100 ml of broth in which our meat was cooked. Add cream and flour to it, and beat everything well with a fork. Set aside.
I hope you still have the broth. Since we will need another 400 ml of our broth. Add tomato paste to it. Here I must say that you can do without it, but then the color of the gravy will not be so beautiful)) Bring the broth to a boil.
As soon as it boils, we take the broth with cream (which we did not set aside for a long time) and pour it into the boiling broth, stirring constantly.
Let it boil again and cook until thickened. That's all. Our gravy is ready, it remains to cool it slightly.
Take the finished casserole out of the oven and let it cool down a little right in the mold.
Bon appetit!