Freeze: Chill a large bowl, a box grater, and the butter in the freezer for 20 minutes before making the pastry.
Rub In Butter: Place the flour and salt in the chilled bowl and whisk together. Grate the butter using the chilled grater into the flour. Rub the butter into the flour until you have a pebble-like crumbly texture. You can do this by pinching and rubbing the butter and flour between your fingers.
Sour Cream: Create a well in the centre of the mixture and add the sour cream. Using a fork to slowly mix the flour into the sour cream in the centre until most of the flour is moist and you have a pebble-like texture.
Shape & Chill: Lightly dust a work surface with flour and shape the dough into a disc. (The dough should be firm and moist, but not sticky. You want just enough moisture so the dough is barely sticking to itself. If it needs more moisture, slightly wet your hands when working with it or, if it’s too dry, lightly dust it with flour.) Cover with plastic wrap and leave to rest in the fridge for 1 - 2 hours, or ideally overnight.
Lamination: Using a rolling pin, roll the dough out into a 2 cm thick and long rectangle. Fold the dough into thirds as if you were folding a piece of paper to go into an envelope. Turn the dough clockwise and roll it back out into a 2 cm thick rectangle. Repeat this step six times until you have created many layers and the dough is smooth.
Chill: Divide the dough into two and wrap each piece in plastic wrap. Leave to rest in the fridge for a minimum of 15 minutes or up to 2 days. If you are not using within 2 days, you can store in the freezer for 3 months.
Filling
Render: In a cold fry pan, add the bacon or pancetta.Turn the heat to low and cook until the fat has been rendered. Once there is enough fat in the pan, turn the heat to high – medium and cook until the bacon or pancetta is crispy. Using a slotted spoon, remove from the pan.
Chicken: Add the chicken to the pan and cook in the bacon fat for 6 minutes or until golden on the outside and cooked through. Remove from the pan.
Mushrooms & aromatics: Add 4 tbsp of the butter to the pan. Once melted and sizzling, add the mushrooms and cook for 5 minutes. Season with salt and stir through. Remove the mushrooms from the pan and add the remaining butter. Add the leek and cook for 5 minutes or until wilted. Add the garlic and cook for an additional 2 minutes.
Deglaze: Deglaze the pan with white wine. Using a wooden spoon, scrape any brown bits off the bottom of the pan.
Flour: Add the flour and stir through for 2 minutes. We want to cook off the flour taste and texture.
Filling: Add the chicken, bacon, mushrooms, cream, mustard, thyme, lemon juice and salt and pepper back to the pan. Stir through and bring to a simmer. Simmer for 3 – 5 minutes. Remove from the heat and leave the filling to slightly cool.
Pie Assembly
Preheat: Preheat the oven to 180°C (355°F).
Assemble: To a pie dish, add the filling.
Roll out Pastry: Take one disc of the homemade puff pastry or 1 sheet of store bought puff pastry. Sprinkle your kitchen bench or work surface with flour. Using a rolling pin, roll the dough out to a large circle that is roughly 4 mm thick and 25 cm wide. Roll the dough onto the rolling pin and roll over the pie dish. Crimp the edges, brush the pastry with egg wash and sprinkle sesame seeds all over.
Bake: Bake for 35 –40 minutes, until golden and crispy.
Serve: Serve immediately!
Notes
Allow the filling to cool slightly before topping with pastry
Always cut small slits in the pastry to allow steam to escape
Egg wash the pastry for extra colour and shine
Do not skip seasoning. Taste the filling before assembling
If using store bought pastry (25cm/10" square), keep it cold until ready to use
Let the pie rest for 10 minutes before serving so the filling sets