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 strips using a chef's knife.
Place the mushroom strips in a gastronorm container.
Pre-cook in the oven to remove excess water.
Unroll the puff pastry on a lightly floured work surface.
Distribute the pre-cooked mushroom strips evenly.
Add the Roquefort cheese and thyme.
Fold the edges of the pastry over, pinching to create a crimped edge.
Generously brush the edges with egg wash.
Evenly cover the entire surface with Cover the tart with grated Parmesan, including the edges. Bake the tart until golden brown and crispy.