Clean and dry the mushrooms.
Place each mushroom with the rounded side down (stem up) on the work surface.
Cut each mushroom in half, then slice each half into 3 mm thick slices using a chef's knife.
Place the mushroom slices in a gastronorm container.
Pre-cook in the oven to remove excess water.
Unroll the puff pastry on a lightly floured work surface.
Spread the blue cheese evenly over the pastry, leaving a 1 cm border.
Distribute the pre-cooked mushroom slices evenly over the cheese.
Roll up the pastry from the long side to form a tight roll.
Brush the end edge with beaten egg yolk to seal. dough.
Using a sharp knife, cut slices 3 to 4 cm thick.
Arrange the snails on a baking sheet lined with parchment paper, leaving 2 cm between each one.
Generously brush each snail with the remaining egg yolk.
Bake the snails until they are golden brown and crispy.