Potato and minced meat casserole with cheese sauce

I have previously published a recipe for potato casserole on the site (link at the end of the post). Since that moment, a lot of time and experience has passed with the preparation of this dish. And finally, I achieved that the casserole suited me completely. Juicy minced meat with pieces of potato in a delicate sauce and the aroma of cheese. And the main condition is that a piece of casserole keeps its shape and does not fall apart on the plate.
Adjust servings in the full version
The first version of potato casserole is located here.
Fry the minced meat in a hot frying pan. Today I have chicken thigh. Add finely chopped onion. Fry everything together until golden brown. Add salt, pepper and spices. Today I have a mixture of Italian herbs. Add a little water, cover with a lid and simmer over low heat until soft. Chicken takes about 15 minutes. Pork stews for 20-25 minutes, beef - 30-35. You may need to add water during the simmering process.
While the minced meat is cooked under the lid in a frying pan, prepare the potatoes. Cut the washed and peeled tubers into thin slices. Lightly spray a baking dish with vegetable oil and lay out half the potatoes. The circles are laid out overlapping. Try not to leave large gaps.
Place the prepared minced meat on top of the potato slices. Distribute it evenly over the entire surface. Place potatoes on top again. In the same way, overlap, leaving no voids. Sprinkle the top layer a little with vegetable oil to prevent it from drying out, and put the pan in the oven for 15 minutes. By this time the oven should already be preheated to 200-230°C.
At this time, prepare the sauce. In a glass of cold milk, dilute 2 full tablespoons of flour. We put the rest of the milk on the stove. Pour the diluted flour into the boiling milk and, stirring all the time (I use a whisk), let the sauce thicken.
Keep stirring to prevent sticking. Season with salt, pepper and spices, then add 100 grams of processed cheese, about half a pack. Stir until completely melted into the sauce.
Pour hot sauce over the potatoes and minced meat and place the pan back in the oven for another 20 minutes. During this time, the potatoes should become completely soft.