• Preheat oven to 400º. Line a rimmed baking sheet with parchment paper.
• Roll out both sheets of puff pastry into a square. Cut each sheet in half so that you have 4 squares. Spread the cheese spread over half of each square, leaving a ½ inch border.
• Dry the chicken breasts with a paper towel. Salt and pepper both sides and place one on top of the cheese spread on each of the four squares. Use a pastry brush to brush water on the edges of the puff pastry. Fold the pastry over the chicken breast and pinch the edges to seal. Transfer to the prepared baking sheet.
• Whisk the egg with a tablespoon of water and brush over the tops of the puff pastry bundles. Bake for 20 minutes until golden brown and a meat thermometer registers 165º.

Sauce:

• Melt butter in a saucepan. Add shallots and cook over medium heat for 2 minutes until slightly softened. Add chicken broth and turn up the heat, cooking until it has reduced by half, about 6-8 minutes. Add the cream and continue cooking until slightly thickened, about 3 minutes. Add mustard and salt and pepper to taste. Serve warm.