Mix crust ingredients in a food processor to form a soft dough.
Press into a 250 mm quiche dish, prick base with a fork and chill.
For filling, sauté onions and spring onions in butter until translucent.
Remove and set aside.
Sauté bacon in the same pan until almost crisp.
Transfer onions and bacon to quiche dish.
Beat rest of ingredients together and pour over.
Bake in a preheated oven at 180°C for 40 - 45 minutes until set.