Clean the pork removing the silver skin – It’s that shiny white-silver membrane running along one side of the tenderloin with a sharp knife

Then butterfly the tenderloin slice it length wise almost all way through- think open book.

Pound it with a meat mallet or rolling pin until it’s an even thickness, about 1/2 inch thick. salt and pepper to taste.

Make the filling

In a saute pan over medium high heat in the olive oil and butter saute the shallots and garlic until soft and translucent

Add the mushrooms cook until brown and all the liquid is absorbed.

In a bowl slightly beat the egg, add in the breadcrumbs, parmesan cheese, parsley and the cooked mushroom mixture. Mix to combine

Spread the stuffing down the center of the pork tenderloin

Carefully roll it up jelly roll style. Then tightly wrap it in plastic wrap and chill for at least 30 minutes.

Then unwrap and spread with the mustard and roast in a preheated 400- degree oven for 10 minutes. Set aside and cool slightly just enough time to handle without burning your hands, then spread with the mustard

On a lightly floured broad roll out the puff pastry and place the pork roll in the center. Wrap the pastry around it. tucking in the edges.

Place it seam-side down on a parchment lined baking sheet

Brush the top with a slightly beaten egg yolk. Score the top. Bake in a preheated oven for 25-30 minutes or until the puff pastry is golden brown.

Let rest for 10 minutes before slicing.