Cut the onion into strips and fry in butter.
Cut the mushrooms into thin large pieces, add to the onion.
Pour in the juice of half a lemon at once, do not salt, add spices, cover and put out everything.
We are preparing a white sauce. Melt 30 g of butter in a saucepan with a thick bottom, add 2 tablespoons of flour.
It is better to use white and very finely ground flour to make the sauce.
Then pour 500 ml of milk in a thin stream, constantly stirring the flour with a spatula. Turn down the heat and leave to boil for 30-40 minutes.
At the end, add a little nutmeg.
We put mushrooms and onions in julienne molds, add cheese, mix a little. Pour over the sauce.
Sprinkle cheese on top. Bake in the oven for 15 minutes at 180 degrees.
Enjoy your meal!
It's delicious to put Dor-blue with mushrooms.