Chicken Pan Pie

Ingredients (15)

• + ¼ cup unsalted butter add to pantry
• + ⅔ cup diced onion add to pantry
• + ½ teaspoon kosher salt, or to taste add to pantry
• ✓ 1 ½ pounds boneless, skinless chicken thighs, cut into 1-inch pieces
• + ¼ cup all-purpose flour add to pantry
• + 2 ½ cups chicken broth add to pantry
• + ½ cup sliced carrots add to pantry
• + ½ cup sliced celery add to pantry
• + ¼ teaspoon freshly ground black pepper add to pantry
• + 1 pinch cayenne pepper add to pantry
• + ½ cup frozen peas, thawed add to pantry
• + 1 teaspoon fresh thyme leaves add to pantry
• + 1 recipe pastry pie dough add to pantry
• ✓ 1 large egg, beaten
• + 2 teaspoons water add to pantry