Dominic Franks on Instagram: "Upside Down Chicken, Leek and Mushroom Pie Welcome back to Upside Down Cooking and we’re sticking with the comfort food this chilly weekend with this Chicken, Leek and Mushroom Pie. For the cheesy sauce: • 500ml milk • 25g flour • 50g butter • 100g strong cheddar – finely grated • 1 tablespoon @paysanbretonuk cream cheese • Salt and pepper For the pie: • 1 sheet of ready-rolled puff pastry, roughly 35 x 23cm • drizzle of extra-virgin olive…