Peel the quince and cut each of them into eight pieces. Remove the cores and put the wedges in an oven-ready dish that just fits them. Scatter over the caster sugar, bay leaves and cinnamon and 250ml water. Cover with tin foil and bake for 1 hour at 170°C/Fan 150°C.
Meanwhile, make the topping. Rub the butter and flour together between your hands until it resembles coarse breadcrumbs. Add the oats, light brown sugar and cobnuts and mix well.
After the hour is up, remove the tin foil from the dish (be careful of the steam). Peel and grate the bramley apple and stir into the quince.
Sprinkle the crumble onto the fruit and bake at 190°C/Fan 170°C for 20-25 mins until the top has browned and the mixture has cooked.
Allow to rest for 10 mins or so, as the sticky fruity juices are red hot and have a habit of burning the roof of your mouth, as I have found out all too often in my haste for a spoonful! Eat with a big dollop of very thick cream or your favourite custard – or hey, why not both?