Begin this recipe a day ahead to marinate the crab.
30 gmbutter½lemonTo serve:micro-basilCourt bouillon and mud crab½small fennel bulb, chopped1golden shallot, chopped5black peppercorns500 ml(2 cups) white wine2lemons, sliced1mud crab (1.5kg), chilled, brain spiked, brought back to room temperature, tail flap removedGascony butter1 headgarlic150 gmsoft butter1 tspfinely chopped flat-leaf parsley1 tspfinely chopped shallotFinelygrated rind of 1 lemon1 tspDijon mustard½ tspcayenne pepperBread crisps½dense loaf of bread30 gmbutter, softened
For court bouillon and mud crab, place fennel, shallot and peppercorns in a saucepan with 3 litres water and bring to the boil over high heat. Once boiling, pour in the wine and bring back to the boil. Add the sliced lemon rounds and crab, bring back to the boil, then remove from heat. Set aside to cool completely, then refrigerate overnight.
The next day, remove the crab from the bouillon and carefully break apart, saving the liquid from the head. Carefully pick all the meat from the crab, ensuring the meat is free of shell and remains in large flakes. Store the meat covered in the fridge.
For the Gascony butter, preheat oven to 160C and slice the garlic in half crossways. Place cut-side down in a small, ovenproof pan with 50gm butter and roast until golden and tender (25-30 minutes). Remove from the oven, then, when cool enough to handle, pop the garlic from the skin and mash with a fork. Mix together with the remaining ingredients in a bowl and season with salt and pepper.
For the bread crisps, slice the loaf into 1mm-thick slices on a meat slicer, or slice very thinly with a very sharp knife. Using a 6cm round cutter, cut the bread into rounds. You’ll need 16, but make extra in case of breakages. Place a sheet of baking paper on a heavy, flat tray, brush the paper with butter and place the bread rounds on top. Brush another sheet of paper with butter, place butter-side down on the bread and top with another heavy tray. Bake in the oven until bread rounds are golden and crisp (10-20 minutes).
To assemble, gently melt butter in a pan over low heat. Add 1 tbsp of the reserved crab juices and gently stir until emulsified. Add 1 tsp of Gascony butter, then remove from the heat and fold into the crab. Season with salt and a squeeze of lemon. Sandwich crab between toast rounds, garnish with micro-basil and serve.