How do you prevent apples going mushy in crumble? Bramley apples (also known as cooking apples) will cook down and become beautifully soft and fluffy. If you prefer more distinct apple pieces, use eating apples and reduce the sugar quantity a little (as they are naturally sweeter than Bramley apples). Why is my crumble topping not crumbly? Using plenty of butter is they key to a good crumble topping, but take care not to over-mix when rubbing it in as that can make your crumble doughy (if you use a food processor take particular care). You can use your fingers to encourage clumps after rubbing in the butter (watch the How-to video below). To further encourage clumps, sprinkle over a little cold water and stir – it will make the crumbs stick together in lumps. Using a mixture of demerara and a finer brown sugar adds a pleasing crunch to your crumble, too. Can you put oats in a crumble mix? Oats are a lovely addition to crumble mixes and give great texture as well as a healthy dose