Preheat oven to 400 degrees. While oven is preheating, chop up mushrooms and leeks. In a skillet, heat olive oil over medium heat and add in chopped leeks. Cook for about 5 minutes on their own, then add in mushrooms and season mixture with salt and pepper. Make sure mushrooms are cooked through, then turn heat off. Next roll out 2 sheets of puff pastry and shred gruyere cheese. Divide shredded cheese in half and spread each half on a puff pastry cheese. Then divide leek and mushroom mixture in half and spread each half over cheese. Line baking sheet with aluminum foil then roll each sheet tightly up. Brush each roll up with egg wash then cut into 1-1.5 inch pinwheels. Place pinwheels flat side down on baking sheet then bake for 20-25 minutes until golden brown. If you want to brown the other side, flip over and bake for another 5 minutes. Take out of oven, let cool for 5-10 minutes, then enjoy!
