Chicken rolls in milk mushroom sauce

My next experiment in the kitchen.
1. Peel and finely chop the onion, cut the mushrooms as small as possible. Fry the onion in vegetable oil, then add the mushrooms there and fry everything until ready.
2. Preparing the base for the sauce. In a saucepan, melt the butter, add flour and stir thoroughly (such a gruel should turn out). Then pour the milk in a thin stream, stirring constantly, bring it to a homogeneous consistency. Salt, pepper and warm up for another 5-7 minutes.
3. A small amount of mushrooms (about 2st.l.) is left for the filling. Mix the remaining mushrooms with the base and whisk with a blender until smooth. The sauce is ready.
4. My fillet and dry it. Each piece of fillet is cut into 2 parts. We will not need a small fillet (we put it in the refrigerator, you can cook something else, for example a salad). Each piece of fillet, wrap with a film and lightly beat off (do not overdo it). Salt and pepper fillets from 2 sides.
5. For the filling, three cheese on a coarse grater, add the postponed mushrooms with onions, garlic, chz press and sour cream, mix well. Salt tastes good. My cheese was salty, so I didn't put the filling on it.
6. We form rolls: we spread a salt spoon of filling on a piece of fillet, distribute it to half a piece and roll it up, fix it with a toothpick. Fry the rolls in vegetable oil until golden brown. Then reduce the heat, pour the sauce over the rolls and simmer everything for about 20 minutes. You can serve such rolls with any side dish. They go very well with rice or mashed potatoes.
P.S, by the way, this wonderful sauce can be used with other dishes, for example, served with pasta, stew meatballs in it, serve with vegetable cutlets, and it will go well with red fish. So try, experiment. There is no limit to fantasy.