• Preheat the oven to 180 degrees (160 degrees fan)

To make the jam

• Place the blueberies in a saucepan and gently cook on a medium heat, stirring intermittently, until they start to turn soft (about 10 minutes)
• Add the flour to the pan and continue to stir through for a further 10 minutes
• Pour the mixture into a blender and blitz until smooth then place to one side

To make the crumble

• Seperate 250g of oats and use a blender to create oat flour
• In a large bowl, place the oat flour and rest of the dry ingredients and mix together with a spoon
• Add the melted butter and vanilla essence to the bowl containing the dry ingredients and mix well until combined into a thick crumble-like consistency

Making the bars

• Line an oven-proof dish with grease-proof paper (or use extra butter to line the tray if preferred)
• Spoon 2/3 of the crumble into the base of the dish and press down with the back of a spoon or by using your hands
• On top of the pressed crumble layer, pour over the thickened blueberry jam layer and even out with a spatula
• Crumble the remaining 1/3 of crumble mix over the top of the jam layer
• Bake for 30-35 minutes until golden
• Remove from the oven and leave to cool completely in the dish before slicing
• Cut into 12 large squares and enjoy either warm with custard or on-the-go