Using an egg cutter, cut the top off the large eggs and pour out the contents. Dry the egg shells out.
Put the egg yolks in a bowl, add the caster sugar and vanilla seeds. Whisk together until pale, fluffy and well combined.
In a small pan, bring the milk and cream to a gentle boil. Gradually pour over the egg mixture.
Pour the mix back in the pan and cook until it has thickened, and coats the back of a spoon. Leave aside to cool.
Carefully ladle the mixture into the dried egg shells. Just before serving sprinkle the demerara sugar on top and carmelise it using a chef's blowtorch.
For the almonds, preheat the oven to 130C/110C Fan/Gas 1 and line a baking tray.
Lightly beat the egg white with 1 tablespoon water. Add the almonds and stir until well-coated. Mix the sugar and salt together and sprinkle over the nuts. Toss to coat, and spread evenly on the tray.
Cook for 1 hour in the oven, stirring occasionally, until golden-brown. Leave to cool.
Increase the oven temperature to 200C/180C Fan/Gas 6.
Put the rhubarb in a roasting tin. Sprinkle over the sugar, then drizzle over the juice. Roast the rhubarb in the oven for 8-12 minutes, or until just tender. Leave to cool. Place in a blender and blend until smooth.
Serve the crème brûlée egg on a serving plate alongside the rhubarb purée and sugared almonds.