Six portions of ground-beef cottage pie with a golden mashed-potato topping.

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Heat oven to 400°F. Cover 2 lb peeled potato chunks with cold water in a pot, bring to a boil and simmer about 15–20 minutes until fork-tender. Drain thoroughly, then mash with 1/2 cup warm milk, 3 tbsp butter and 1/2 tsp of the 1 tsp salt. Keep the mash thick enough to spread, not pour.
While potatoes simmer, cook 1 1/4 lb ground beef in a large skillet over medium heat, breaking it up until a thermometer verifies 160°F. Drain excess fat. Add 1 tbsp olive oil only if the pan is dry, then soften 1 diced onion and 2 small-diced carrots about 7 minutes. Add 2 minced garlic cloves for one minute.
Stir in 2 tbsp tomato paste and 2 tbsp flour, cook one minute, then gradually stir in 1 cup low-sodium beef broth, 1 tbsp Worcestershire, 1 tsp thyme, remaining 1/2 tsp salt and 1/4 tsp pepper. Simmer until a spoon dragged across the pan leaves a brief trail. Fold in 1 cup frozen peas and transfer to a 9-inch square dish.
Spread mashed potatoes edge to edge over the hot beef filling and roughen the surface with a fork. Bake at 400°F about 25–35 minutes until the top has golden ridges and the filling bubbles at edges. Rest 10 minutes before six portions. Check pan capacity and final reheated filling temperature during a kitchen test.

Recipe-development draft; not kitchen-tested. Timing and yield are estimates. Nutrition has not been calculated.

Additional chilling, resting or cooling time: 10 minutes, included in the total.

Untested estimate: potatoes boil about 20 minutes while beef cooks up to 20 minutes, bake up to 35 minutes, rest 10 minutes; preheat excluded.