Place the sheet of puff pastry on a tray lined with baking paper.
In a small bowl, combine eggs and milk and whisk with a fork. Add the cheese. Heat a frying pan and add a little oil. Scramble the eggs until just cooked and set aside.
In a medium bowl, add the chicken, spinach, egg and garlic aioli (or mayonnaise). Mix well and season with salt and pepper.
Place mixture on one half of the sheet of pastry and even out. Fold over the pastry to close and press a 2 cm border around the edges using the back of a fork.
Preheat oven to 220 degrees and bake for approx 20 minutes.