First, make the rhubarb granita. Place the rhubarb in a vac bag with the sugar and seal tightly. Place in a pan of simmering water until all of the juice has been relased, the rhubarb breaks down and appears overcooked

Alternatively, poach the rhubarb by adding it to a saucepan with about 250ml of water. Cover and cook on a low heat for approximately 20 minutes until the rhubarb has softened. Stir in half of the sugar and simmer, uncovered, until about 30ml of liquid is left. Take off the heat and allow to cool - it should look a little bit like very wet stewed fruit

Once the rhubarb is completely soft and cooked, transfer the contents of the bag or pan into a chinois and drain the juice into a bowl

Pour half the juice into a small flat tub and place in the freezer. Scrape every half an hour with a fork until completely set and the ice resembles red snow

For the gel, stir in 1.1g of agar agar for every 100ml of the remaining hot juice and set in the fridge. Once set, blend until smooth and store in a squeezy bottle until required

Preheat the oven to 160°C/gas mark 3

For the shortbread, cream the butter, sugar and vanilla extract together in a mixing bowl until light and fluffy. Gently mix in the flours until just combined

Once the mix has formed a smooth dough, shape into a ball, wrap in cling film and leave to chill in the fridge to rest for approximately 20 minutes. Then, on a lightly floured surface, roll out to 1cm thick and cut into finger shapes

Transfer the shortbread fingers onto a lined baking tray and bake in the oven for 10-12 minutes until golden. If the dough feels very soft before baking, place back into the fridge to chill and firm up for 10-15 minutes to help hold its shape

Reduce the oven to 95°C

To make the baked custards, place the milk, cream and vanilla into a pan and bring to a simmer

Meanwhile, thoroughly whisk the yolks and sugar until thick, pale and creamy. Remove the hot cream mixture from the heat and slowly pour into the yolks while whisking. Use a ladle to skim off any bubbles that rise to the surface

Pour into ramekins or kilner jars and use a blowtorch to knock out any last bubbles, or alternatively use a small piece of cling film to dab the surface of the liquid to remove the bubbles

Place on a tray and into the oven for 30-45 minutes until the custard is just set and has a slight wobble to it. There s not need for a bain marie due to the low oven temperature

To make the batons, place the rhubarb in a vac pac bag with the sugar and seal tightly. Place in a pan of simmering water (80˚C) until tender, but still holding its shape, approximately 15-20 minutes

To plate, top the custard with a generous spoonful of the rhubarb granita. Add a smear of rhubarb gel to the plate and top with poached rhubarb batons. Place the shortbread biscuits alongside the rhubarb and serve