Peel the potatoes and cut them into slices about 1/2 cm thick, bring them to the boil in salted water and let them steep for 5 minutes! Drain and keep warm.
Melt the butter, dust the flour over it and make a light roux while stirring. If the flour is a little roasted, first deglaze with the hot meat stock, then with the milk, stirring constantly, and season with salt. Bring to the boil, stir, reduce a little and then add the potato slices. Simmer gently until the potatoes are cooked through.
Just before serving, add the warmed cream and sprinkle with the parsley.