Preheat the oven to 190°C (375°F). Lightly butter individual ramekins or cleaned crab shells if using.
Finely chop the Onion, slice the Leek thinly, dice the Tomato, mince the Garlic, and roughly chop the Parsley.
Warm a generous glug of Extra-virgin Olive Oil in a wide sauté pan over medium heat. Add the onion and leek and cook until soft and translucent, about 6–8 minutes.
Add the tomato and garlic and cook until the tomato breaks down and the mixture is fragrant, 4–5 minutes. Stir occasionally so nothing sticks.
Carefully add the Brandy to deglaze the pan; let it bubble and reduce for a minute (you may flambé if you like), then pour in the Dry White Wine and reduce until most of the liquid has evaporated.
Pour in the Fish Stock, bring to a gentle simmer and reduce for a few minutes until the sauce is slightly thickened. Season with a pinch of Cayenne Pepper, Salt and Black Pepper to taste.
Fold in the Cooked Spider Crab Meat and warm through briefly—be gentle so the meat keeps some texture. Adjust seasoning if needed and stir in most of the chopped parsley.
Remove the pan from the heat and mix in the majority of the Fine Breadcrumbs and several small knobs of cold Unsalted Butter until the mixture binds but remains moist. Reserve a little breadcrumbs and butter for the topping.
Spoon the crab mixture into the prepared ramekins or shells, sprinkle the reserved breadcrumbs over each portion and dot with the remaining butter.
Bake in the preheated oven until the topping is golden brown and bubbling, about 12–15 minutes. Let rest a couple of minutes, then finish with the remaining chopped parsley and serve warm with crusty bread or a simple salad.
