Shepherd’s Pie

Cover potatoes with water and 1 T. salt in medium saucepan. Bring to boil over high heat, lower heat and simmer until potatoes are soft, 8 to 10 minutes. Drain completely and return to saucepan. Remove pan from heat, mash potatoes well and stir in melted butter. Whisk together milk and egg yolk in small bowl, then stir into potatoes. Stir in scallion greens and season with salt and pepper to taste. Cover and set aside.

Heat oil in broiler-safe 10-inch skillet over medium heat until shimmering. Add onion, mushrooms, 1/2 t. salt, and 1/4 t. pepper; cook, stirring occasionally, until vegetables begin to soften and dark bits form on bottom of skillet, 4 to 6 minutes. Stir in tomato paste and garlic; cook until bottom of skillet is dark brown, about 2 minutes. Add Madeira and cook, scraping up any browned bits, until evaporated, about 1 minute. Stir in flour, cook for 1 minute. Add broth, Worcestershire, thyme, bay leaf, and carrots; bring to boil, scraping up any browned bits.

Reduce heat to medium-low, add chicken (beef, turkey or mushrooms) to broth, and bring to gentle simmer. Cover and cook until chicken is cooked through, 10 to 12 minutes, breaking up meat chunks. Stir cornstarch and remaining 2 teaspoons water together in bowl, then add to filling and simmer for 30 seconds. Remove thyme and bay leaf. Season with salt and pepper to taste.

Adjust oven rack 5 inches from broiler element. Turn on broiler. Place mashed potatoes in large zipper-lock bag and snip off 1 corner to create 1-inch opening. Pipe potatoes in even layer over filling, making sure to cover entire surface. Smooth potatoes with back of spoon, then use tines of fork to make ridges over surface. Place skillet on rimmed baking sheet and broil until potatoes are golden brown and crusty and filling is bubbly, 10 to 15 minutes. Let cool for 10 minutes before serving.