Step #1 Heat oven to 190°C
Roll out the pastry on a lightly floured surface & use to line a deep 23cm fluted flan tin.
Step #2 Line with baking paper & fill with baking beans.
Step #3 Bake blind for 15 mins.
Step #4 Heat the butter & oil In a large-ish frying pan, then carefully fry the onions, covered, for about 30 mins until completely softened, but still pale in colour.
Step #5 Beat the eggs & cream together in a bowl, then add the cheese & some seasoning.
Step #6 Stir in the onions, then spoon the mixture into the flan case.
Step #7 Bake for 25-30 mins until lightly set & browned.