Preheat oven to 400°. In a bowl, lightly mix beef and dressing mix. Shape into eight 1/2 inch thick patties.

In a skillet, cook burgers over medium heat for 3 minutes on each side or until a thermometer reads 160°.

On a floured surface, unfold puff pastry; roll into a 12 inch square. Cut pastry into four 6 inch squares; cut squares in half to make eight rectangulars. Place a burger on one end of each rectangle; top with cheese. Brush edges of pastry with egg mixture. Fold pastry over burger; press edges with a fork to seal. Transfer to a parchment paper lined baking sheet. Brush with egg mixture. Bake 15-20 minutes or until golden brown.