Preheat oven to 180 C/ 350 F/ Gas 4. Place onions in a saucepan and add 1tbsp of spread. Cover and cook over a low heat for 10 minutes. Stir in garlic, parsley, sugar and vinegar and cook uncovered for 10 minutes.
Cut each pastry sheet in two and brush with remaining melted spread. Line 4, 10cm/ 4in loosebottomed tins with two sheets of pastry, scrunching edges to form a rim.
Bake for 6 minutes, remove from the oven. Turn upside down and cook for a further 5 minutes.
Remove from oven, place correct way up. Spoon onion mixture and cheese triangles into each pastry case. Cook for 10 minutes, covering with foil. 5. Season and garnish with salad leaves and parsley.