In a large enough sauteed pan, on medium to high heat, put in the butter.
Add the snails, shallots, mushrooms and sauteed until the mushroom get really soft, 6 to 10 minutes.
Add the garlic. Do not burn the chopped garlic. Deglaze with the brandy, be careful if the flames get it not to burn yourself.
Add the beef base (mixed with water) and reduce by 1/3, 3-5 minutes.
Add the parsley and tarragon.
Add the cream and turn the heat on low to medium, let it reduce a little for a better texture, 3-4 minutes.
Taste and season with salt and pepper.
For serving: on a plate or small bowl, place the bottom of the puff pastry, ladle the snail and mushroom ragout equally (make sure each plate get 6 snails), place the top puff pastry. Serve immediately.