Cottage Pie

Heat the oven to 350 degrees.

Prepare the filling: Heat an ovenproof 12-inch skillet over medium. Add ground beef and a large pinch of salt and cook, breaking up the meat as you go, until slightly pink and just cooked through, 5 to 7 minutes. Using a slotted spoon, transfer the ground beef to a bowl and set aside. Leave about a teaspoon of fat in the pan and discard the rest.

To the same skillet, add butter, onion, celery and carrot and a pinch of salt. Cook, stirring occasionally, until the onion is translucent and the carrot is just tender, about 5 minutes. Add the garlic and tomato paste, stirring to coat, about 1 minute. Add flour and stir to incorporate.

Add broth, red wine, peas, Worcestershire sauce, thyme sprigs, bay leaves and 1 teaspoon each salt and pepper. Stir to combine, then bring to a simmer and cook, stirring occasionally, until the consistency of thick gravy, 7 to 10 minutes. Taste and add extra seasoning, if needed. Remove the bay leaves and thyme sprigs and stir in the ground beef. Remove from heat and set aside to cool slightly.

Make the topping: To a large saucepan, add 4 quarts of water and 2 tablespoons of salt and bring to a boil. Add potatoes and cook until knife-tender, about 15 minutes. Drain the potatoes and put back into the saucepan. Add the milk, 4 tablespoons butter and ½ cup grated Parmesan. Mash with a potato masher until just creamy, avoiding over-mashing. Taste and add salt if needed.

Dollop the mashed potatoes on top of the beef mixture in the skillet, carefully smoothing the mashed potatoes until it fully covers the beef mixture and reaches the edge of the pan. Drizzle the remaining 1 tablespoon of butter over the top, sprinkle with remaining ¼ cup grated Parmesan and bake in the oven until golden and bubbly, about 30 minutes. Let stand for 10 minutes before serving.