1largecooking apple (eg Bramley)peeled, cored and cut into small pieces
300gblackberriesfresh (washed) or frozen
120gcaster sugarsuperfine sugar
3large eggs At room temperature - beaten (UK large = Canadian ‘Extra Large’; Australian ‘Jumbo’; and US ‘Extra or Very Large’)
Wash the jam jars and lids in warm soapy water and rinse thoroughly. Do not dry.
Wash any silicone seals (from Kilner jars) separately with hot soapy water and set aside.
Place the clean jars and their lids (but not the silicone seals from Kilner jars) into a cold oven on a baking tray and turn the oven on to 170 C/325 F/Gas 3. Allow to heat whilst you make your puree. Once the oven has reached temperature, the jars should be allowed to heat for about 15 to 20 minutes.
Once the jars have sterilised, turn off the oven, but leave the jars to cool in the oven, until ready to use.
Preparing the fruit
Place the prepared apple and the blackberries into a saucepan and sprinkle with 1 tablespoon of the sugar.
Add 3 tablespoons of cold water and set on the hob over medium heat and bring to a simmer, stirring.
Allow to simmer, stirring occasionally until the fruit has cooked through and is soft enough to crush with the back of the spoon.
Remove from the heat and leave to cool.
Once cool, puree the fruit using a blender.
Push the puree through a sieve into a bowl or jug to remove any seeds and fibrous bits. This will take some perseverance as you want to get as much puree through as possible
Cooking the Curd
Make a double saucepan by taking a large sturdy saucepan, on top of which you can place a large pyrex (heat-proof glass) bowl so that it sits securely at the top of the pan. Place a few centimetres of water into the bottom of the saucepan and check that the bowl sits above this, without its base touching the water.
Place the butter, all the remaining sugar, eggs and fruit puree into the bowl placed over the saucepan on a hob and begin to heat the pan.
Bring the water to a simmer, while continually stirring the ingredients.
Now turn the heat down to a low simmer and continue to stir, so that the steam under the ingredients is effectively cooking them very slowly. STIR CONTINUALLY. Do NOT turn up the heat and be really patient with the cooking process or you will scramble the egg.
Keep stirring until the butter melts and the mixture thickens into a custard consistency which coats the back of the spoon and holds its thickness. This may take 15+ minutes.
Once cooked, pour the curd into your sterile, warm jars and seal with lids immediately. Set aside to cool.
Once cold, store in the fridge.
* Note: nutritional information is an estimate & may vary according to portion size/ingredient variants.