500 g ready made shortcrust pastry
1 large onion , sliced
1 garlic clove , crushed
200 g kale , washed and roughly chopped
10 pitted green olives , halved
150 g Gruyère , grated
1 egg , beaten
Heat oven to 190C/gas 5. Roll out the pastry to about 2cm thickness and line a 23cm tart tin. Bake blind for 15 minutes. Cook the onion in a large knob of butter until softened, then add the garlic and kale and cook for a few minutes until the kale has softened and wilted. Mix in the olives and cool. Stir most of the cheese and the egg into the kale mix, then tip it into the tart tin. Sprinkle the rest of the cheese on top.
Bake for 20-25 minutes until the pastry is crisp. Serve warm with a green salad.