Shallot and yoghurt quiche

The most delicious and authentically quiche-like quiche I have ever eaten

When I tried making it, the filling came out all soggy. I haven't tried again. User error, or sabotage?

Better Homes, June 1987. Serves 6. 9 steps

1-2 sheets wholemeal pastry				Line 20cm flan dish, prick base, bake in moderately hot oven 15 minutes
2 eggs			beat	Pour in, bake in moderate oven 30 minutes or until set
1 cup Swiss cheese	grated		add
1 cup plain yoghurt
1 tablespoon parsley	chopped
salt and pepper
30g butter		cook until soft, cool
2 cups shallots	slice finely

Serve warm with vegetables as a main course, or with a crisp salad

Or use Spanish red onions