Remove the outer leaves from the pointed cabbage. Cut the cabbage into 8 slices. Wash the carrots and clean them so that a little green is preserved. Steam cabbage in a pot with little water for about 8 minutes until al dente.
Steam the carrots in a smaller pot also with a little water for about 5 minutes. In the meantime melt the fat. Sweat flour in it. Add stock and cream while stirring constantly, bring to the boil and simmer for another 2 minutes.
Season to taste with salt and pepper. Grate cheese, stir 50 g into the sauce. Carefully lift out cabbage with a skimmer and rinse with cold water. Remove the stalk from the cabbage slices so that the leaves do not fall apart.
Wrap 1 slice of cured pork sausage around each of the cabbage slices and layer in a greased casserole dish. Put carrots between the slices. Pour cheese sauce over them and sprinkle with 100 g Gouda. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 35 minutes.
Remove the gratin and let it cool down briefly. Garnish with chervil.