Heat a drizzle of oil in a large, non-stick pan and add the chicken. Fry on a medium heat for around 5 minutes, or until no longer pink. Remove from the pan and set aside.
Add the onion to the pan and fry for 5 minutes until soft. Stir in the garlic for the final minute.
Stir in the flour until it disappears.
Slowly add the chicken stock a little at a time, only adding more when it comes to the boil. Stir continuously.
When all the stock is used, stir in the cream, oregano, sun-dried tomatoes and grated cheese. Gently bring to the boil, stirring until the cheese has melted.
Season with salt and pepper.
Return the chicken to the pan with the spinach and give it a good stir.
Divide the filling between 4 deep individual pie dishes, approximately 12cm across.
Heat the oven to 190C (fan).
Roll out the pastry. Cut out 4 squares of pastry that will just fit on top of your pie dishes.
Lay them on top of the dishes and press the corners down so they stay in place.
Cut 8 heart shapes and 8 slightly smaller heart shapes out of the pastry.
Arrange them on top of the pastry square, pressing them gently together. Brush with beaten egg.
Bake in the oven for 20-25 minutes until cooked through and golden brown on top.
