Mix flour with salt. Add the cold butter in pieces and egg and quickly knead into a shortcrust pastry. Refrigerate.
Preheat the oven to 200 degrees top / bottom heat.
Thaw the savoy cabbage and squeeze out a little. Clean the mushrooms and cut into slices. For the topping, whisk the eggs, stir in the cream and parmesan, season with salt, pepper, nutmeg and rosemary.
Roll out the dough to the size of the baking sheet (use a drip pan!) And form a small edge. Spread the savoy cabbage and mushrooms on the dough, pour the topping evenly over the top.
Bake for approx. 40 minutes, possibly cover after 30 minutes or switch to bottom heat.
Tip: You can of course spice up the quiche with bacon cubes or sliced almonds under the vegetable layer, if it does not have to be vegetarian or if you do not have allergy sufferers.