Preheat the oven to 400 degrees F.

On a lightly floured surface, roll out each pastry sheet to an 11-inch square. Using a 4-inch puff pastry cutter with middle insert, cut 3 rounds from each sheet, saving the scraps for another use. If you don't have a cutter with a middle insert, you can cut out 4-inch circles and then use a 2 1/2-inch cutter to remove the middle round.

Place 2-inches apart on an ungreased cookie sheet and bake until golden brown, 18 to 20 minutes. Remove from the oven and gently lift off the top and reserve the top. Scoop out and discard the soft inner pastry. Return the shells to the oven and bake until starting to crisp, about 3 minutes. Remove and let cool.

In a large skillet or saute pan, melt the butter over medium-high heat. Add the shallots and garlic and cook, stirring, until soft, about 3 minutes. Add the flour and stirring constantly, cook for 2 minutes. Add the tomato paste and cook, stirring, for 1 minute. Add the cream, brandy, lemon juice, salt, and cayenne, and whisk to combine. Cook, stirring, until the sauce thickens, 3 to 4 minutes. Add the crawfish tails and cook until warmed through, 2 to 3 minutes. Remove from the heat and adjust the seasoning, to taste.

Arrange the puff pastry rounds on 6 plates. Divide the crawfish cardinale among the pastry shells and place the tops slightly off center. Garnish each plate with the green onions, parsley and paprika, with watercress on the side.