1 can of snails. The easy one to find here is Musette 20-22 count per can, I believe those are imported from Thailand.
The Escargots de Bourgogne are big, but in Belgium we have the "petits gris de Namur" and in France you can also find a "gros gris" [fat grey] If they are too big for you shells you can cut them in 2, it will not affect the preparation.
for the paste:
1 stick of butter [salt or unsalted] 6 garlic cloves, finely chopped ½ bunch of fresh parsley finely chopped Fresh ground pepper to taste, I like a lot of it. Salt if the butter was unsalted
METHOD
Mix all paste ingredients together In each shell put half a teaspoon of the mixture, add the snail, and fill with another ½ teaspoon of butter . [This can be done days ahead and kept in the freezer.] Arrange on a snail plate and transfer in a 400 preheated oven for 10 minutes max. Serve with French bread and a bottle of red Burgundy.
HINT
There is a way to stuff the snails in the shells.
Insert the body part first twisting it clockwise into the shell.