Chicken, Leek and Tarragon Pot Pie

Ингредиенты

• 3 tbsp unsalted butter, softened
• 1/4 cup (40 g) unbleached all-purpose flour
• 4 tsp cornstarch
• 1/2 cup (125 ml) milk
• 3 cups (285 g) leeks, thinly sliced
• 2 tbsp unsalted butter
• 2 1/2 cups (625 ml) chicken broth
• 1 cup (160 g) russet potatoes, peeled and diced
• 1 1/2 cups (255 g) cooked chicken, diced (about 1/2 store-bought roasted chicken)
• 3 tbsp tarragon leaves, finely chopped (see note)
• 2 cups (300 g) unbleached all-purpose flour
• 1/2 tsp salt
• 1 cup (225 g) cold unsalted butter, thinly sliced
• 2/3 cup (150 ml) ice water
• 1 egg yolk
• 2 tbsp (30 ml) milk