Peel and slice the carrots. Then cook in a little salted water until al dente. When the carrots are cooked, strain them, catching the water and setting aside.
Heat the butter in a saucepan and add the flour. Sweat briefly and then deglaze with 100 ml carrot water and the cream. Simmer on a low flame for about 10 minutes so that the flour taste disappears. Then sprinkle in the parsley, add the carrots and heat everything quickly and season with salt, pepper and a pinch of sugar. If the sauce is too thick, dilute it with a little more carrot water.