Preheat the oven to 160C/140 Fan/Gas 3.
In a bowl, beat together the brown crab meat, egg yolks, nutmeg, milk and cream. Season with salt and pepper.
Pass the mixture through a sieve into a clean, large bowl, pressing all of the liquid out of the crab meat.
Pour the mixture into four ramekin dishes. Bake for 20 minutes, or until set. It will depend on the size of the ramekin. Leave to cool.
In a clean bowl, toss the white crab meat with the spring onion and olive oil.
Place the tomatoes around the outside of the custard pots, spoon over the white crab meat mixture, squeeze over the lemon, sprinkle with the micro basil and serve.