Prep your pastry and tin: Preheat the oven to 400°F (200°C).
Line a 9-inch (23 cm) pie dish with one sheet of pastry, pressing gently into the edges. Trim excess. Prick the base with a fork and chill while you make the filling.
Soften the leeks: Warm the olive oil or butter in a large skillet over medium heat.
Add leeks, onion, and carrot with a pinch of salt. Cook 6–8 minutes until soft and fragrant, stirring often. Add garlic and cook 1 minute more.
Brown the pork: Push the vegetables to the side of the pan.
Add the minced pork to the empty space and cook until no longer pink, breaking it up with a spoon. Stir everything together.
Season the mixture: Add thyme, sage, pepper, smoked paprika (if using), and remaining salt. Stir in the Dijon and Worcestershire sauce.
Cook 1–2 minutes to bloom the flavors.
Thicken the filling: Sprinkle the flour over the mixture and stir for 1 minute. Slowly add chicken stock, then milk or cream, stirring until it becomes a thick, glossy sauce that coats the meat and leeks. Simmer 2–3 minutes.
Adjust seasoning and stir in parsley if using. Let cool 10–15 minutes so it doesn’t melt the pastry.
Assemble the pie: Spoon the cooled filling into the chilled pastry-lined dish. Top with the second sheet of pastry.
Trim and crimp the edges to seal. Cut 3–4 small slits in the top to vent steam. Brush with beaten egg for a glossy finish.
Bake: Place the pie on a baking sheet.
Bake 30–35 minutes until the pastry is puffed and deep golden and the filling is bubbling at the edges.
Rest and serve: Let the pie rest 10 minutes before slicing. Serve with a simple green salad or your favorite greens.