Thaw the puff pastry according to the package instructions.

Heat the olive oil and brown the onion and garlic in it.

Add the mushroom and sauté until wilted and the cooking liquid evaporates, then turn off the heat and let it cool.

Season the filet mignon with salt and pepper.

In a frying pan, heat a drizzle of olive oil and sear the filet mignon quickly until golden on all sides, using tongs to avoid piercing the meat.

Turn off the heat and pat the filet mignon dry with a paper towel.

On a piece of plastic wrap, lay out the Parma ham slices, the mushroom filling and the filet mignon.

Roll it up using the plastic wrap, like a rocambole, and chill for 1 to 2 hours.

Sprinkle the breadcrumbs over the pastry and place the filet mignon with the filling on top.

Close the longer sides first, then the shorter sides.

Place on a baking tray with the seam facing down.

Create the desired decoration and brush with the beaten whole egg.

Bake in a preheated oven at 180°C for approximately 40 minutes or until golden.

Remove from the oven, wait about 10 minutes, and serve.