Chicken Shepherd's Pie | America's Test Kitchen

Ingredients

• 2 pounds bone-in chicken thighs , trimmed
• Salt and pepper
• 6 tablespoons unsalted butter , cut into 6 pieces
• 1 onion , chopped
• 3 carrots , peeled, halved lengthwise, and cut crosswise 1/2 inch thick
• 2 garlic cloves , minced
• 1 1/2 teaspoons minced fresh thyme
• 1/4 cup dry sherry
• 2 cups chicken broth
• 2 pounds russet potatoes , peeled and cut into 1-inch chunks
• 1/4 cup cornstarch
• 1 cup frozen peas , thawed
• 1 tablespoon lemon juice
• 1 large egg , lightly beaten