Make the pastry (recipe from Bbcgoodfood website). Chill for 30 mins minimum. Whilst pastry chills, chop onions, and sauté with the sugar, in butter for 5-10 minutes. When cool,mix with cheese,and plenty of seasoning. Blind bake pastry case in 20 cm quiche/tart tin. Add cheese and onion filling to cooked pastry case. Mix eggs and milk,and pour into quiche tin. Bake for 50 mins on 170 fan/ 180 conventional oven. When cool enough to handle, remove quiche from tin.