To make meatloaf: Soak breadcrumbs in milk for 5 minutes. Combine Ground Beef with all other meatloaf ingredients in a bowl. Mix gently until just combined. Shape into a firm 8-inch log. Place on a parchment-lined tray and chill for 30 minutes.

To make duxelle mixture: Heat oil in large skillet over high heat. Sauté mushrooms, shallot and garlic over medium heat 10 to 15 minutes or until dry and deeply browned. Add thyme, season to taste. Let cool completely.

To make crepes: Blanch spinach in boiling water for 15 seconds, shock in ice bath. Squeeze dry. Blend spinach and milk until smooth. Add eggs, flour, butter, salt, and blend. Rest batter for 20 minutes. Cook crêpes in a lightly greased 10-inch nonstick pan over medium heat. Pour in a ladle, swirl, and cook 1 minutes per side. Cool.

To assemble: Lay spinach crêpe flat on a board. Layer prosciutto slices over crêpe in a slightly overlapping pattern. Spread mushroom duxelles over prosciutto. Place chilled meatloaf log at the base and roll tightly into a cylinder using the crêpe as a barrier. Wrap in plastic and chill 10 to 15 minutes to set the shape.

On a floured surface, roll out puff pastry, if needed. Place wrapped meatloaf seam-side down in the center of pastry. Fold pastry over tightly, sealing edges with egg wash. Trim excess pastry and crimp ends. Place seam-side down on parchment-lined baking sheet.

Brush exterior with egg wash. Chill again for 10 to 15 minutes. Preheat oven to 400°F. Brush again with egg wash and lightly score a decorative pattern with a paring knife.

Bake 40 to 50 minutes or until pastry is golden and internal temp reaches 160°F. Rest 10 to 15 minutes before slicing.