Onions peel and halve. Clean, wash and cut the spring onions into pieces. Dice the bacon and leave it crispy in a pan. Add onions and spring onions and fry for four minutes, turning. Mix crème fraîche and eggs and season with salt and pepper. Roll out the short pastry (left over from the apple tart) on a floured work surface to a circle (31 cm Ø), place it in the greased tart tin (28 cm Ø) and prick the base several times with a fork. Place the vegetables and bacon cubes on the pastry base, pour the egg crème fraîche over them and bake in the preheated oven (electric range: 200 °C/ gas: level 3) for 45 to 50 minutes