Ingredients

• 2 cups chicken stock
• 3 boneless, skinless chicken breasts
• 5 tablespoons butter, divided
• 2 leeks, sliced
• 2 cloves garlic, minced
• 1/3 cup all-purpose flour
• 3/4 cup whole milk
• 3 tablespoons white wine (optional)
• 2/3 cup heavy cream
• about 1 cup (5 oz) cooked ham, diced
• to taste sea salt
• to taste black pepper
• 2 3/4 cups all-purpose flour (for pastry)
• 14 tablespoons cold butter, cubed (for pastry)
• 1 egg, beaten (for pastry)
• 1 tablespoon cold water
• 1 egg, beaten (for glaze)

Equipment

• Lidded saucepan
• Heavy saucepan
• Food processor
• Rolling pin
• Pie dish
• Baking sheet

Instructions

1. Pour the chicken stock into a lidded saucepan and bring to a low simmer. Add the chicken breasts, cover, and poach gently for about 10 minutes, until just cooked through and no longer pink in the center. Lift the chicken onto a plate with tongs and pour the cooking liquid into a measuring cup to reserve.
2. Melt 2 tablespoons of the butter in a heavy saucepan over low heat. Add the sliced leeks and cook gently for about 2 minutes, stirring, until they soften and turn bright green without browning. Stir in the garlic and cook another minute until fragrant.
3. Add the remaining 3 tablespoons butter and, once melted, stir in the 1/3 cup flour. Cook for 30 seconds, stirring constantly, so the raw flour taste cooks out and the base for your sauce forms.
4. Slowly whisk in the milk a splash at a time, stirring well between each addition to keep the sauce smooth. Gradually add about 1 cup of the reserved stock and the wine, if using, stirring until the sauce thickens slightly. Bring to a gentle simmer and cook for 3 minutes.
5. Season the sauce with salt and pepper to taste, then remove from the heat and stir in the heavy cream. Pour into a bowl, press plastic wrap right onto the surface to stop a skin forming, and let it cool completely.
6. For the pastry, pulse the 2 3/4 cups flour and cold butter in a food processor until the mixture looks like fine crumbs. With the motor running, add the beaten egg and cold water and blend just until it gathers into a ball. Set aside about a third of the dough for the lid.
7. Preheat the oven to 400 degrees F and slide a baking sheet in to heat. Roll the larger piece of dough on a floured surface to about 1/4 inch thick and a couple inches wider than your pie dish. Drape it over the rolling pin, ease it into the dish, and press it firmly up the sides with no air pockets, leaving the excess hanging over.
8. Cut the poached chicken into bite-size 1-inch pieces. Stir the chicken, diced ham, and leeks into the cooled sauce, then pour the filling into the lined dish. Brush the pastry rim with beaten egg.
9. Roll out the reserved dough for the lid and lay it over the filling. Press the edges together firmly to seal, then trim the overhang. Cut a small vent hole in the center with a knife tip and brush the top all over with beaten egg.
10. Bake on the hot baking sheet in the center of the oven for 35 to 40 minutes, until the crust is deep golden brown and the filling is bubbling hot. Let it rest a few minutes before slicing so it holds together.