Wash the potatoes and cook covered in water for about 20 minutes
Peel, wash and cut the kohlrabi into thin slices. Boil 1/4 l water with the broth. Steam covered kohlrabi for about 5 minutes. Drain, catching the broth
Heat the fat. Sweat flour in it while stirring. Deglaze with milk and stock while stirring, bring to the boil. Let the sauce simmer for about 5 minutes. Stir in processed cheese in flakes. Season to taste with nutmeg, pepper and salt if necessary
Quench the potatoes and remove the skin. Let the potatoes cool down a little. Cut into slices. Layer with kohlrabi and cured pork loin (possibly cut in half) in a greased gratin dish (approx. 26 cm Ø). Pour the sauce over them. Grate the Gouda roughly and sprinkle over it. Bake in a preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) for 20-25 minutes until golden brown. Garnish if necessary