Heat the olive oil in a heavy bottomed saucepan, over a medium heat. Slice the chicken into 3cm pieces, seasoning generously with sea salt and fry each side until golden brown.
Remove the chicken with a slotted spoon and add the mushrooms and lardons to the saucepan, frying until they have changed colour. Remove and set aside with the chicken.
Over a lower heat, melt the butter and stir in the flour to make a roux. Allow to cook for a few minutes, whisking continuously and gradually add the stock, followed by the cream.
Return the chicken, mushrooms and lardons to the pan, stirring into the creamy sauce. Add the TruffleHunter Black Truffle Oil and finally the kale, stirring and allowing to cook for 2 - 3 minutes. Check the seasoning, adjust accordingly
Heat the oven to 220C. On a floured surface, roll the pastry out thinly and cover the pie, tucking the sides into the dish. With a pastry brush, coat the surface with the beaten egg. Bake for 30 minutes, until the pastry is crispy and golden.