1Place milk, flour, and butter in a pan and whisk until melted and thickened (about 5 mins). Stir in cheeses and set aside.
2Place milk, flour, and butter in a pan and whisk until melted and thickened (about 5 mins). Stir in cheeses and set aside.
3Place milk, flour, and butter in a pan and whisk until melted and thickened (about 5 mins). Stir in cheeses and set aside.
4Preheat oven to 200°C fan/425°F. Place pastry on a baking tray lined with parchment paper; drizzle with olive oil and sprinkle with thyme, salt, and pepper.
5Preheat oven to 200°C fan/425°F. Place pastry on a baking tray lined with parchment paper; drizzle with olive oil and sprinkle with thyme, salt, and pepper.
6Preheat oven to 200°C fan/425°F. Place pastry on a baking tray lined with parchment paper; drizzle with olive oil and sprinkle with thyme, salt, and pepper.
7Scatter mushrooms, leeks, and shredded chicken evenly over the pastry, leaving a 1cm border.
8Scatter mushrooms, leeks, and shredded chicken evenly over the pastry, leaving a 1cm border.
9Scatter mushrooms, leeks, and shredded chicken evenly over the pastry, leaving a 1cm border.
10Pour half the cheese sauce over the chicken, leeks, and mushrooms.
11Pour half the cheese sauce over the chicken, leeks, and mushrooms.
12Pour half the cheese sauce over the chicken, leeks, and mushrooms.
13Drape puff pastry over the filling; press edges to seal. Score the top with a knife and brush with egg.
14Drape puff pastry over the filling; press edges to seal. Score the top with a knife and brush with egg.
15Drape puff pastry over the filling; press edges to seal. Score the top with a knife and brush with egg.
16Bake for 30 minutes until golden and puffy. Let sit for 5 minutes, then carefully flip onto a chopping board, peel off parchment paper, and bake for another 5 minutes to brown the top and bubble the cheese.
17Bake for 30 minutes until golden and puffy. Let sit for 5 minutes, then carefully flip onto a chopping board, peel off parchment paper, and bake for another 5 minutes to brown the top and bubble the cheese.
18Bake for 30 minutes until golden and puffy. Let sit for 5 minutes, then carefully flip onto a chopping board, peel off parchment paper, and bake for another 5 minutes to brown the top and bubble the cheese.