Sprinkle crawfish tails with Creole seasoning, set aside.
Measure and chop all other ingredients, and place in prep bowls. Combine the Herb and Spice Blend into a small prep bowl. Preheat the oven to 350 degrees (or whatever temperature the puff pastry instructions call for).
Place a 12” saute pan (or similar) over medium heat, add the butter.
When the butter is bubbly, add the yellow onions and saute for about 2 minutes.
Add the garlic and continue to saute until aromatic, about 2 minutes.
Add the AP flour to the onions and garlic. Stir or whisk constantly to make a light roux, about 3 minutes.
Next, add the Worchestershire Sauce and the Herb and Spice Blend. Combine and saute for about 1 minute.
Raise the heat slightly, then add the Stock. Bring the stock to a low simmer and maintain for about 20 minutes as the stock reduces.
Once the stock has reduced and slightly thickened, add the Crawfish tails and green onions. Stir to combine thoroughly. Simmer for about 3 minutes
Next, add the heavy cream and sherry. Stir to mix well. Adjust the heat to continue on a low simmer until the mixture thickens to a semi-thick sauce, this will take about 20 minutes.
Bake the puff pastry according to the package directions. Remove them to a cooling rack. When slightly cooled, remove the caps.
When the sauce has thickened slightly, remove the pan from the heat and allow the sauce to cool for about 5 to 10 minutes while you prepare the puff pastry.
After baking the puff pastry, fill each shell to just overflowing with the crawfish sauce. Replace the pastry top if desired.