Add corn flour to the boiling cream in a thin stream, stirring constantly with a wooden spoon in one direction. Reduce the heat to low and stir constantly. Stir until oil droplets appear on the walls and surface of the porridge, and the porridge does not begin to lag behind the bottom and walls of the pan, “dancing”. If the sour cream is store-bought, you know – there is not a drop of milk in it, there will be no butter… After 15 minutes, remove from the heat, place on a platter and sprinkle with cheese, grated on a fine grater.