Knead 250 g flour, 125 g soft butter and a little salt. Add the egg and about 1 1/2 tbsp. cold water and knead everything into a smooth dough. Put in a cool place for about 1 hour
Clean, wash and finely chop the leek. Steam in 30 g hot butter for about 5 minutes. Sprinkle with 1 tbsp. flour and sweat. Add cream and simmer for about 2 minutes. Grate cheese, stir in 60 g of it. Season with salt, pepper and nutmeg
Knead the dough and roll out to a circle (32 cm Ø). Line a greased quiche or springform pan (approx. 28 cm Ø) with the dough and press it up along the edge. Prick the base several times. Pre-bake in a hot oven (electric cooker: 200 °C/ convection oven: 175 °C/gas: level 3) for 20 minutes
Spread the leek mixture on the floor. Spread the remaining cheese and 20 g butter in flakes on top. Bake for 25-30 minutes