Cheddar cheese and onion tart

I pride myself on being able to make dinner out of what looks like nothing. I get into this zone where I think I’m in some kind of Ready Steady Cook-style competition and get all excited about how I can make a 3 course dinner out of an old bag of nuts and an egg. I didn’t make a 3 course dinner, I just made a tart, but still.
It’s good for using up any odds and ends of cheese, this tart. Chuck ‘em all in there. I used the fading remains of a block of cheddar plus 3 types of onion: red, white and spring. The pastry was shop-bought, knocking around in the freezer. It was rich, filling and mmmm cheesy. Not bad for a bit of fridge foraging.
Cheddar cheese and onion tart
150g cheddar cheese, crumbled
2 large red onions, sliced into thin half moons
2 medium white onions, sliced into thin half moons
4 spring onions, finely chopped (white and green parts)
1 clove garlic, crushed
1 sprig rosemary (or thyme), leaves removed and finely chopped
2 eggs
100ml double cream
250g shortcrust pastry
Salt and white (or black) pepper
This recipe fills a 24cm tart dish.
Begin by caramelising the onions. Heat 2 tablespoons of vegetable or groundnut oil in a heavy based frying pan and add the red and white onions. Once they are sizzling, turn the heat down as low as possible and let them cook gently for about an hour, stirring every so often, until very soft and caramelised.
Preheat the oven to 190C/fan 170C/gas 5. Roll out the pastry to fit the dish and carefully lay it in, covering the base and sides. You want the pastry to overhang the sides by a couple of centimetres, as it will shrink during cooking. Make sure to patch up any holes. Fill the pastry base with baking beans (or dried beans or rice) and cook for ten minutes before removing from the oven and setting aside.
Mix the cheese with the spring onions, rosemary, eggs, cream and caramelised onions when ready. Season with salt and white pepper. Pour the filling onto the tart base and spread evenly. Bake for 25-30 minutes until golden brown.