Preheat oven
Heat the oven to 220° C and move a rack to the upper third so the topping browns quickly at the end.
Prep the filling
Peel and finely chop the onion. Trim the leeks, split them lengthwise, rinse out any grit, and finely chop the white part. Peel and finely chop the tomato, mince the garlic, chop the parsley, and flake the spider crab meat gently with your fingers to check for any shell fragments.
Cook the base
Warm the extra virgin olive oil in a wide skillet over medium heat. Add the onion and leeks and cook, stirring often, for 8 minutes until soft and glossy, then stir in the garlic and tomato and cook for 5 minutes more until the tomato has broken down and the mixture looks jammy.
Deglaze and reduce
Pour in the brandy and stir up any browned bits from the pan. Let it bubble for 1 minute, then add the dry white wine and warm fish stock and simmer for 10 minutes until the liquid has reduced to a moist, spoonable filling.
Season the filling
Take the pan off the heat and fold in the spider crab meat and parsley. Season with the cayenne pepper a little at a time, stirring until the filling tastes warm, balanced, and just firm enough to mound in the shell.
Fill the shells
Spoon the filling into the reserved shells, mound it gently, and scatter the fine breadcrumbs over the top. Finish with small dots of unsalted butter so the crust turns crisp and golden.
Gratin the shells
Set the shells on a baking tray and broil on the upper rack for 4 minutes, or until the breadcrumbs are deep golden and the butter is sizzling. Serve immediately while the filling is hot.















