Finely chop the onions

Cut peppers in half and pull out seeds and membrane

Cut into strips and then across into medium dice

Trim mushroom stems and wipe mushrooms clean with damp paper towels

Slice mushrooms and finely dice

Mince parsley and then chop prosciutto. Melt butter in a large skillet over medium high heat

Add the onions and cook 5 minutes

Stir in mushrooms and bell pepper and cook, stirring often, until mushrooms are tender and all liquid has cooked off

Add the prosciutto and Marsala and cook, stirring until liquid is evaporated. Remove to a bowl and stir in parsley and breadcrumbs

Season with salt and pepper to taste and cool completely.Preheat oven to 400 degrees

Line two baking sheets with parchment paper

On a lightly floured work surface roll out the puff pastry to a 15 x 9 inch rectangle

Cut each sheet into 3 strips across and 5 strips down to make 30 total squares

Preheat oven to 400 degrees

Lightly brush two adjacent sides with the egg wash

Spoon 2 teaspoons mushroom filling onto square and fold in half to form a triangle

Press to seal edges and then crimp with a fork

Poke the top of each with the fork as well

Transfer turnovers to baking sheets and brush with egg wash

Bake for 15 to 18 minutes or until golden brown

Serve warm.