Preheat the oven to 200C/400F and line a baking tray.

Place blackberries, cornflour, sugar and lemon juice into a medium sized saucepan and place over a low-medium heat. Stir frequently and bring to a boil.

Once boiling, stir continuously until the mixture is thick and the blackberries are soft. It should stick to your spoon.spatula. Turn off the heat and then use a fork to gently mash the blackberries. Leaving a few lumps is absolutely fine! In fact I loved having larger and small lumps of blackberry for variety!

Leave to one side whilst you prepare the puff pastry: Place the sheet off puff pastry onto your lined baking sheet, then divide it into thirds by very lightly scoring two lines along the length of the pastry. Leave the centre of the pastry as it is.

With the outer two "sections", cut the corner off at the top of each side, to give you a guide for your braids. Then mark every 3/4-1inch and follow your diagonal edge to slice each braid. I had 11 braids on each side of my pastry. Once you've sliced the last braid, there will be a triangle at the bottom of each side of the pastry, cut this out and discard.

Spoon the blackberry filling into the centre of your pastry, all the way along. You may have some leftover. Smooth it out with the back of a spoon, you want a good layer, but not so much it's completely over flowing and going everywhere. My filling was around 1/2 an inch thick.

Take the first braid of the right side and bring it over the filling, then the left side, repeat until you get to the bottom. At the top and bottom there will be a flat part of pastry, bring it up and join it to your braids to tuck in the filling.

Place an egg into a small cup and beat lightly. Brush the egg over the top of your pastry, it doesn't matter about getting every nook and cranny, but make sure you get the tops of all the braids and the ends.

Place in the oven for 17-22 minutes until rise, puffy and golden on top. The filling should be bubbling slightly at the ends.

Remove from the oven and leave to cool completely on the tray (you can also serve it warm).

Once cool, if desired, make the glaze: place the icing sugar into a small bowl and add 1tsp of water at a time, stirring in between each addition, until you have a smooth mixture which coats a spoon, but still drizzles off. Use a spoon to drizzle the glaze all over the cooled braid.

Blackberry Braid is best served the same day, but is still good the next day if kept in an airtight container at room temperature.. If you keep it longer than 2 days, it will go soft.