a mushroom and gruyère tart

Oh, the wonderful world of ready-made puff pastry. Buy a  500g block, cut it into six pieces*, and freeze them. They take no time at all to defrost and are perfect as the basis for a simple mid-week dinner. Roll a piece out to your desired thickness and make the shape you require - a rectangle, square or round. Add your chosen toppings, bung in the oven for 20 minutes or so and serve with a crisp, green salad and maybe some sautéed potatoes or a hunk of good bread. There's already a few ideas in the recipe section:

• taleggio and onion tart
• gruyère and chorizo tart with a poached egg
• asparagus and parmesan tart
• pancetta and mushroom tart
  
• goat's cheese tart
  

* Unwrap the pastry block and divide in half lengthways. Cut each half into three equal-sized pieces. Wrap each piece in cling-film and freeze.

And here's a recipe for a mushroom tart I made last night:

serves 2
a slice of butter
½ onion, chopped
1 garlic clove, crushed
150g baby chestnut mushrooms (halved or quartered depending on size)
1 tbsp fresh thyme leaves
2 tbsps apple juice
2 tbsps double cream
100g gruyère, grated
salt + black pepper
2 x portions of puff pastry (see above)

Melt the slice of butter in a pan, add the onion and garlic and fry gently until softened. Add the mushrooms and thyme and fry until cooked through. Turn up the heat a little, add the apple juice and cook until there's almost no liquid left. Now add the cream and cheese and a goodly amount of black pepper. Stir until the cheese has melted. Taste and add salt as required - it won't need a lot, if any.

Roll the pastry portions into two 165mm x 125mm rectangles. With a sharp knife, score the two rectangles 10mm in from each edge. Bake on a baking tray in a  200C/180C fan oven for 10 minutes. Remove from the oven. The pastry will have puffed up. Flatten the insides of each piece with the back of a spatula, so you have a distinct border to hold in the filling.

Divide the filling between the two pastry cases and return to the oven for approximately 15 minutes, checking after 10 minutes, until the pastry borders are crisp and golden.