Preheat oven to 450°F. Grease a sheet pan with melted butter then set aside. Thaw puff pastry according to manufacturer's instructions. Set aside. In a large Dutch oven, melt ¼ cup butter until lightly browned. Add apples then sauté 3–5 minutes or until lightly browned, stirring occasionally. Add honey and salt, mixing well to incorporate. Place pot in oven and roast 15 minutes or until apples are soft. Remove from oven and transfer apples to a large mixing bowl. Mash apples with a fork while they are still warm. Let apples cool to room temperature then gently fold in blueberries. Reduce oven temperature to 400°F. In a small mixing bowl, beat egg with water and set aside. In a separate small bowl, mix together cinnamon and granulated sugar. Set aside. Lay the thawed puff pastry out flat onto floured work surface. Cut 4 large circles out of each pastry with a (5-inch) ring cutter. Continue until all pies are filled. Brush egg wash on the outer edge of each pastry round. Spoon 2 tablespoons apple-berry mixture into center then fold each round over to cover filling, making a semi-circle and seal edges with a fork. Place pies on prepared sheet pan and cut air holes into the top of each pie. Brush the top of each pie with egg wash. Sprinkle with cinnamon sugar mixture then bake 20–25 minutes or until puffed and golden brown. Remove from oven, garnish with powdered sugar and serve immediately.