For the crabs: Boil crabs in plenty of salted water, remove and drain for about 12 minutes. Crack crabs while still warm. Remove meat and shred. Set aside Corail and creamy parts.
For the dough: Melt 50 grams (approximately 2 ounces) butter. Combine flour, beaten egg whites, sugar and a pinch of salt and stir in butter. Let rest for about 20 minutes.
For the filling: Peel and grate carrot and celery and cook for 5 minutes in remaining butter. Stir in corail and creamy parts with fish stock and cognac. Puree mixture in a blender.
Preheat the oven to 220°C (approximately 430°F).
Line a baking sheet with parchment paper. Divide dough into 12 approximately 8 cm (approximately 3 inch) circles. lay on parchment paper. Sprinkle with poppy seeds and bake until golden brown, about 8 minutes.
Combine crab meat and vegetable puree. Heat briefly heat and season with salt and pepper.
Layer pastry circles with crab filling on plates, garnish with dill and serve immediately.