Sift flour into large bowl. Combine yeast with milk and add to flour. Stir in sugar, salt, egg and oil, mix to a soft, sticky dough. Cover and stand in a warm place for about 30 minutes. Dust over with a little flour and roll into a thin longish cake base. Spread generously with crème fraiche and season with pepper and nutmeg. Cut onions into thin slices, mix with bacon bits and spread mixture on tarte. Bake in hot oven (about 200°C) for about 35 minutes.