One of my favourites is caramelised red onion and creme fraise tart:
Buy ready rolled puff pastry, cut to fit a round tart case
Cook pastry on its own for about 10-15 mins (160C) until brown and risen (make sure pastry is fully sealed!)
Fry thinly sliced red onions in butter, fresh thyme and garlic for about 10 mins
Layer onions in cooked pastry case, pour in a tub of creme fraise
Sprinkle olive oil on top and cook in oven (200C) for 1 min....lovely