For the Lorraine bacon pie, place flour and salt in a large bowl. Cut the butter into small pieces, add it and rub it into the flour. Then add the egg and milk and mix quickly with a knife to distribute evenly. Press the mixture into a ball by hand. The dough should be able to be formed into a compact ball. Let rest in the refrigerator for at least 60 minutes.
Roll out the dough on a floured surface to 31-32 cm ø. Place in a buttered tart or springform pan about 28 cm ø. Trim off any overhanging dough. Prick the bottom of the dough with a fork at regular intervals. Chill the dough again while preparing the filling.
Cut the bacon into small cubes, leek and onion into strips, sauté everything with a little fat, then spread evenly over the short pastry base.
Beat the eggs with a fork until foamy and add the whipped cream. Salt the whipped cream only very lightly, after all the bacon already contains salt. Season to taste with pepper and nutmeg.
Carefully pour the glaze over the cubes and immediately bake in a preheated oven at 180° C (convection oven 170° C) for about 35-45 min until the whipped cream mixture has set.
Take out the Lorraine bacon cake and wait 1-2 minutes before cutting the cake.