Prepare jacket potatoes, let cool, peel and cut into slices.
Let the onion cubes in the butter become translucent, dust with flour and sweat a little, deglaze with wine and milk, bring to the boil and then simmer gently for about 5 minutes and season well.
Layer the potatoes and the onion sauce alternately in a baking dish, then pour the cheese and cream on top.
Place in the oven for about 1/2 hour at 225 ° C.
Tastes great and is something different than the same potato gratin over and over again.