Heat 3 tablespoons of olive oil then add mushrooms until golden.
Add chicken and keep frying until beginning to colour.
Add chicken stock pot and cream, and then simmer for 5 minutes.
Transfer chicken to an oven dish.
Brush edge of the dish with water, then cut strips of pastry to line the edge.
Brush pastry strips with more water then top with the remaining pastry to form a lid, pinch the edges to secure.
Brush with remaining tablespoon of butter, then cut the top to form a vent for steam to escape.
Bake at 200 C until the pastry is cooked through, golden and crisp.