Blackberry & Bay Parfait, Rosemary & Chocolate Shortbread Crumb |Only Cookery. Start by lining a loaf tin with clingfilm, covering both sides of the film with a neutral oil like rapeseed. Gently heat your blackberries in a small pan, with a splash of water and squeeze of lemon. After around 15 minutes, you can push them through a sieve until you have a thick purée. Set this aside. Dissolve your caster sugar in 150ml of water, along with the bay leaves. Bring up to the boil gently and then leave to infuse for 10 or 15 minutes. Remove the bay leaves. Drop your gelatine into cold water and then set about putting your egg yolks in a pyrex bowl, over some simmering water. At the same time add your sugar & bay syrup, whisking constantly, until starting to thicken. This will take at least 5 minutes if not more. Drop in your gelatine and carry on whisking off the heat for another 5 minutes. Set aside to cool slightly. Combine your cream and blackberry purée, and whisk vigorously until starting to thicken. This could take between 5 and 10 minutes depending on the amount of elbow grease you are willing to spare. Fold in the egg mixture, and combine until silky smooth. Pour into your loaf tin and freeze for at least 4 hours. To make your shortbread, combine the dry ingredients in a mixing bowl and then grate your frozen butter into it. Mix with your fingertips until it resembles fine breadcrumbs. Add your whisked egg and form a ball. Wrap with clingfilm and pop in the freezer for 10 minutes. Set your oven to 200 degrees celsius (180 fan), before lining a baking tray with baking parchment. Roll out the dough flat on a floured service and place into the tray. Cook for 20 minutes, until golden brown. Remove and allow to cool. When it comes to serving, leave the parfait out the freezer for 5 minutes before using a [b]warm knife[/b] to gently pry the parfait out of the tin, then slice, and finally serve with the shortbread alongside.