Step 1

Peel 2 medium carrots and finely dice. Finely dice 2 large celery stalks and 1 large yellow onion. Finely grate or chop 2 garlic cloves.

Step 2

Heat 1 tablespoon of the olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat until shimmering. Add 1 to 1 1/3 pounds lean ground beef and break it up with a wooden spoon. Let cook undisturbed until the bottom is browned, about 5 minutes. Flip and continue to cook until cooked through and any liquid is evaporated, 2 to 3 minutes more.

Step 3

Transfer the beef with a slotted spoon to a plate. Reduce the heat to medium. Add the remaining 2 tablespoons olive oil and onion. Cook, stirring occasionally and scraping any browned bits from the bottom, until the onions start to turn translucent, about 5 minutes. Meanwhile, bring 4 cups low-sodium beef broth to a boil in a medium saucepan over high heat. Add the celery and 1/2 teaspoon of the kosher salt and cook for 5 minutes. Drain the celery in a strainer set over a bowl; reserve the saucepan.

Step 4

Add the celery, carrot, garlic, and 3 large fresh thyme sprigs to the onions. Cook, stirring occasionally, until the carrots start to slightly soften at the edges, about 5 minutes. Return the beef and any accumulated juices to the pot. While stirring continously, add 2 tablespoons tomato paste and sprinkle with 1/4 cup all-purpose flour. Cook, stirring often, until darkened in color, about 2 minutes.

Step 5

Increase the heat to medium-high. Add 1 cup dry red wine and cook for 2 minutes to let alcohol to burn off. Add the reserved broth and 1/4 cup Worcestershire sauce, and bring to a simmer.

Step 6

Reduce the heat to low. Simmer uncovered, stirring occasionally, until the liquid thickens enough to coat the back of a spoon, about 45 minutes. Meanwhile, peel 2 1/2 pounds russet potatoes and cut into 1-inch pieces. Transfer to the reserved medium saucepan and add 2 bay leaves and enough cold water to cover the potatoes. Add 1 1/2 teaspoons of the kosher salt and 1/4 cup of the heavy cream if using. Bring to a boil over medium-high heat. Reduce teh heat as needed and simmer until the potatoes are tender, 15 to 20 minutes.

Step 7

Meanwhile, arrange a rack in the upper third of the oven and heat the oven to 375℉. When the potatoes are almost ready, place 3/4 cup whole milk and 4 tablespoons unsalted butter in a small microwave-safe bowl. Microwave until the butter is melted and the milk is warm, 1 to 2 minutes. (Alternatively, heat in a small saucepan over medium-low heat.)

Step 8

Drain the potatoes and discard the bay leaves. Return the potatoes to the pot. Place over low heat for 2 minutes, stirring regularly (this dries out potatoes and yields a fluffier mash). Remove the pot from the heat. Pour in about half of the milk mixture and the remaining 1/4 cup heavy cream if using. Mash with a fork or potato masher until lightly mashed. Add the remaining milk mixture in 2 tablespoon increments, continuously beating with a fork, until smooth and creamy or the desired consistency is reached. Add the remaining 1 teaspoon kosher salt and 1/2 teaspoon ground white pepper or black pepper and stir to combine.

Step 9

When the beef is ready, add the remaining 1 teaspoon kosher salt and 1/2 teaspoon ground white or black pepper, and stir to combine. Discard the thyme sprigs. Drain the ground beef mixture through a strainer set over a bowl (you should have about 2 cups gravy).

Step 10

Transfer the beef mixture to an 8x8-inch baking dish and spread into an even layer. Spread the mashed potatoes evenly over the beef, completely covering it and going all the way to the edges of the baking dish. Use a fork to make lines, swirls, or patterns in the potatoes to create a crispy texture. Hold a box grater over the potatoes and grate 1 ounce aged cheddar or Parmesan cheese on the smallest holes evenly over the potatoes.

Step 11

Bake until the cheese is melted and the topping is golden-brown in spots, 25 to 30 minutes. For an extra-crispy topping, turn the broiler on to high and broil until desired crispness, 3 to 5 minutes more. Let rest for 10 minutes before serving.

Step 12

Rewarm the reserved gravy in the microwave for 1 to 2 minutes or in a small saucepan on the stovetop over medium heat for 2 to 3 minutes. Serve the cottage pie with a small drizzle of gravy on top.