Knead the flour with butter, ½ teaspoon salt, baking powder and 4-5 tablespoons water to form a smooth dough. Grease a tart pan or springform pan, line it with the dough and pull up a 2-3 cm high rim. Chill for at least 30 minutes. Wash the asparagus and cut off the ends. Pre-cook in boiling salted water for 4-5 minutes until firm to the bite, drain, rinse in cold water and drain.
Preheat the oven to 180 °. Halve the ham slices lengthways and wrap each asparagus stick with them. Spread 100 g cheese on the bottom of the dough. Place the asparagus spears on top and sprinkle with the rest of the cheese. Whisk the eggs with the crème fraîche, season with salt and pepper and pour over. Bake for about 45 minutes.