Finely chop the ginger and then add all of the jam ingredients (including the syrup from the ginger jar) to a large saucepan and stir. Place on a medium heat and bring to the boil, stirring regularly, until the sugar has all dissolved.

Turn down to a low heat and simmer for around 35-45 minutes, stirring every now and then. The mixture should darken and reduce down. To test it's ready, place a small amount on a chilled metal plate - if the mixture wrinkles when you push it with a spoon it's ready. Take the jam off the heat and cool while you make the crumble.

Preheat the oven to 180'C / Fan 160'C / Gas Mark 4. Line a 20cm square tin with baking paper and set to one side.

Add the melted butter, caster sugar and flour to a large mixing bowl and stir until the mixture starts to come together. Use your hands to create a 'crumble' type texture - kind of like breadcrumbs but some big lumps are really good!

Take two-thirds of the mixture and press it down firmly with a spoon or your fingers into the lined baking tin so that it covers the bottom in an even layer.

Next spoon over the jam, spreading it evenly over the pressed-down crumble mix. Once the jam is spread, add the 50g oats to the remaining crumble mix and then sprinkle over the rest of the mixture evenly and then place in the oven.

Bake for 35-40 minutes until the crumble is lightly golden on top and the fruit mixture is bubbling round the edges. Remove from the oven and cool completely before slicing into 16 squares.