Cheesy Mushroom Spinach Puff Pastry

1.Heat a large skillet over medium heat, then add the butter. Once the butter has melted, add the mushrooms, sauté 5-7 minutes. Add the garlic, sauté 1-2 minutes, then add the spinach and sprinkle the salt and pepper over the top.
2.Saute for an additional 3-4 minutes, then turn the heat off and set the skillet aside. Allow the filling to cool for 20 minutes.
3.Preheat the oven to 425°F. Roll the puff pastry sheet out on to a large piece of parchment paper. Slice a triangle from the bottom of the dough, then slice ½ inch diagonal lines up each side of the pastry, add the fill in the middle.
4.Top filling with cheese. Lay the rectangular end of the puff pastry over the filling, then begin on one side, and lay one strip of dough over the filling, then alternate laying a strip of dough from the other side, then alternate back and forth over the filling. Once the entire puff pastry is wrapped up, transfer it on the parchment paper to a baking sheet.
5.In a small bowl add egg and water and beat well. Brush egg wash over the entire puff pastry. Place into the oven to bake for 25-30 minutes until golden brown. Take the pastry out and transfer to cooling rack. Let the pastry rest for 20 minutes before slicing and serving.