Wash and peel the asparagus. Cut off the woody ends. Cook the asparagus with some sugar in plenty of boiling salted water for 15-20 minutes. Dab cutlets dry and fry them in hot oil for about 4 minutes on each side.
Season with salt and pepper. Drain the asparagus and let it drain. Bring butter sauce and 1/8 litre water to the boil while stirring. Remove from the heat and stir well for about 1/2 minute. Grate cheese finely.
Place 1/4 of the asparagus on each half of a cutlet. Fold the cutlets over it. Place the filled cutlets in a flat casserole dish. Add sauce, sprinkle with cheese and bake in a preheated oven (electric: 200 °C/ gas: level 3) for approx. 10 minutes.
Wash the sage, dab dry and cut into strips, except for a few stems for garnishing. Sprinkle over the gratinated escalopes.