Funguy Chicken Pie

Ingredients

• 200g Swiss Brown mushrooms, sliced
• 600g chicken thighs, diced
• 1 tbsp olive oil
• 2 tbsp butter
• 1 onion, grated
• 1 carrot, grated
• 1 tomato, finely diced
• 1 tbsp flour
• 350ml chicken stock
• 1 tsp Dijon mustard
• 2 tbsp crème fraiche (or thickened cream)
• Few sprigs of fresh thyme and rosemary
• ½ tsp ground nutmeg
• 50g grated tasty cheese
• 1 sheet puff pastry
• 1 egg (lightly beaten)
• Salt
• pepper