Blanch the sausages in hot water for 3-5 min to prevent the skin from bursting. Drain and pat dry.
Heat the clarified butter in a large pan over medium-high heat. Add the sausages and fry until browned, 15 min.
Cut each sausage lengthwise and unfold. Brush the cut surfaces with mustard. Slice the Limburger cheese and layer the slices on the mustard like scales.
Transfer the sausages to a baking tray and bake in a preheated oven at 180°C (350°F) for 10-15 min until the cheese is melted.