For a tart pan of 26 cm ø For the short pastry, cut the cold butter into small cubes.
Mix the flour with the baking powder and the Parmesan cheese, then mix in the butter cubes with the dough hooks of the mixer until crumbles form. Now add the egg and continue mixing until a cohesive dough forms shortly after. Quickly knead the dough briefly and heartily with your hands, form into a ball, wrap in plastic wrap and rest in the refrigerator for half an hour.
Remove the peel from the white asparagus (this may not be necessary for the green). For both types of asparagus, cut the heads about 3 inches long into small pieces and trim at the bottom of the stalk just before the cut end. Boil water in a large saucepan, season with salt, add a little sugar and a knob of butter and simmer both types of asparagus – but without the heads at the beginning – for 10 minutes on low heat, then with the asparagus heads for another 5 minutes. After that the asparagus should be soft, but still have a little bite. Fish out the asparagus spears, cool and cut the spears diagonally into relatively narrow, elongated slices, halving the heads lengthwise.
Cut the chives into fine rolls, mix the eggs with the sour cream or crème fraiche, season with a little salt, pepper and a pinch of nutmeg (freshly grated).
Roll out the shortcrust pastry