Shepherd's Pie (Cheddar Cheese)

4 baking potatoes, peeled and thinly sliced (2 lbs)
coarse sea salt
black pepper, freshly cracked
1 Tbsp. extra-virgin olive oil
6 medium carrots, halved lengthwise, quartered
6 ribs celery, thinly sliced
1 large onion, chopped
½ tsp. dried thyme
¼ cup all-purpose flour, unbleached
¼ cup tomato paste
2 lb ground beef chuck
1 cup whole milk
1½ cups sharp white cheddar, shredded (6 oz)

Preheat oven to 450°F (230°C/210°C fan, Gas Mark 8).

Place potatoes in a large saucepan, and cover by 1” with salted water. Bring to a boil; reduce to a simmer. Cook until potatoes are easily pierced with the tip of a paring knife, 15-20 minutes.

Meanwhile, heat oil in a 5-quart Dutch oven or heavy pot over medium-high. Add carrots, celery, onion, and thyme. Cook, stirring occasionally, until vegetables are tender, 8-10 minutes. Add flour and tomato paste; cook, stirring, 1 minute. Add beef; cook, stirring occasionally, until no longer pink, 6-8 minutes. Add 1 cup water; bring to a boil, and simmer 1 minute. Set beef filling aside.

Drain potatoes; return to pan. Cook over medium, stirring, until liquid has evaporated and a thin film covers bottom of pan, about 1 minute. Remove pan from heat; add milk and 1 cup cheese. Mash until smooth; season cheddar-potato topping with salt and pepper.

Pour beef filling into a 13x9” baking dish. Drop dollops of topping over filling; spread to edges with a spatula. Using a fork, make decorative peaks; sprinkle with remaining ½ cup cheese.

Bake until topping is browned and filling is bubbling rapidly, about 20 minutes (if topping and filling were chilled, increase to 35 minutes). Let stand 5 minutes before serving.

Makes 8 servings.

Cook's Note: Both filling and topping can be made up to a day ahead and refrigerated separately.