Heat olive oil in a medium pan over medium-high heat and sauté the chopped mushrooms until they become tender.
In a bowl combine, the cooked mushrooms, shredded chicken, mozzarella cheese, mayonnaise, garlic, dill, salt, and pepper.
Place the thawed puff pastry shells on a baking sheet lined with parchment paper and fill each shell with 1 heaping tablespoon of the chicken mixture. Then brush with egg wash and bake at 390 degrees Fahrenheit for 30 minutes.
Notes
How to make them in advance: If you're tight on time, you can prep these Mushroom Puff Pastries by making the chicken and mushroom filling ahead of time and then storing it in an airtight container in the fridge until you are ready to fill and bake the shells.How to reheat the mushroom appetizers: Place them on a baking sheet lined with parchment paper and bake at 300 degrees Fahrenheit for about 8 minutes.