Remove the very tops and bases of the fennel bulbs, then cut them lengthwise once or twice, depending on their size. Melt the butter over low heat. Place the fennel in an appropriately sized ovenproof dish and pour the clarified butter over it. Add the star anise. Bake at 140°C for about an hour – or until the fennel is tender. The baking time will vary depending on the size of the fennel.
Set aside some leaves from the pot of basil for use as garnish later, then put the rest of the basil in a blender along with the oil and blitz until completely blended. Let the mixture stew for half an hour, then run it through a fin-meshed sieve, reserving the basil oil for later.
Roast the hazel nuts on a dry pan until they begin to turn golden. Allow them to cool, they chop coarsely.
Arrange the cooled fennel on individual plates. Break off bits of the Castello Traditional Danish Blue cheese and sprinkle over the fennel. Then sprinkle with chopped nuts. Add a dollop of crème fraîche and a drizzle of basil oil. Grind some fresh pepper on top and garnish with basil.