Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a bowl, combine cooked shredded chicken, cream cheese, cheddar cheese, chives, salt, and pepper. Mix until well incorporated.
In another bowl, combine the wilted chopped spinach, cream cheese, and a pinch of salt and pepper. Mix well.
On a lightly floured surface, roll out the puff pastry sheet. Cut it into 3-inch squares.
Place a tablespoon of the chicken mixture in the center of half of the pastry squares and a tablespoon of the spinach mixture in the center of the remaining squares.
Fold the pastry squares over the filling to form triangles. Press the edges with a fork to seal well.
Brush the tops of each pastry with the beaten egg to give them a golden color when baked.
Place the filled pastries on the prepared baking sheet and bake in the preheated oven for 15-18 minutes or until golden brown and puffed.
Once out of the oven, let them cool for a few minutes before serving.
Notes
Serve warm with dipping sauce for an attractive display.