i have made this many times and the recipe comes from a french/belgium restaurant i worked in once again no written recipe , but i will try and explain how i did it.
we bought the escargots (ok, snails) in a a 1 or 2 lb. tub, they came frozen and cleaned, no shells. we had shells we could stuff them in, if needed.
i took a small pyrex ramekin and filled it half full of a clarified unsalted-butter, parsley and a small bit of garlic mixture. i put in 6 snails and covered the top with a puff pastry sheet. i would cut the pastry to fit the ramekin with a little hanging over the sides of the ramekin and coat with a egg wash (egg white and water) and made sure it sealed, use egg wash to make sure, pastry could shrink if not sealed good .
i put in a 425 degree oven and browned the pastry. i would make some kind of design on the pastry from a small cutters, before i browned it. i served this on a small white plate with a small paper doily on it. this dish we sold for $9.95 and sold a bunch nightly.
a few sliced button mushrooms would be an option