Preheat the oven to 400°F. Line a baking sheet with parchment or waxed paper.

Thaw the pastry shells according to package directions. Preheat the oven to 400 degrees F.

Put the pastry shells on the prepared baking sheet and bake according to package directions until golden brown, about 15 minutes. Remove from the oven and let cool.

Set the shells aside to cool while you prepare the filling. Once they are cool, you can remove the top inner segment of pastry; you should now have a small cup to hold the crawfish filling. Reserve the small top of pastry for setting on top of the filled vol au vents if desired.

In a skillet over medium heat, combine the butter and flour and cook, stirring slowly and constantly for 2 to 3 minutes, to make a blond-colored roux. Add the onion and garlic and cook, stirring, for 2 minutes. Slowly whisk in the broth and cook, whisking occasionally, until it thickens slightly, about 25 minutes.

Season the crawfish with the Creole seasoning and add to the sauce. Cook, stirring, for 2 to 3 minutes. Add the cream, Worcestershire, and hot sauce. Cook, stirring, for 1 minute, then stir in the green onions.

Spoon equal amounts of the crawfish and sauce into the center of the pastries and top with the pastry tops. Serve warm.