Heat your oven to 190c.
In a bowl, mix the berries, caster sugar, vanilla, cornflour, orange juice and zest, ensuring the berries are well coated then chill in fridge whilst making the dough.
In another bowl, blend the flour, nuts, spice, muscovado sugar and a pinch of salt, then rub the butter in to make a crumbly dough.
Pour the berry mix into the jars then divide the dough into 4-6 balls, flatten them slightly and push down firmly on the berries like a lid.
Place the jars on a baking tray lined with baking paper and bake for 20-30 minutes until bubbling and brown. Allow to cool slightly before serving or chill, screw lids on and transport for a picnic.