1 tablespoon olive oil 2 celery ribs, chopped fine 1 onion, minced Salt 2 garlic cloves, minced 2 teaspoons minced fresh thyme Pepper 1 1/2 pounds 85-percent lean ground beef 3 tablespoons all-purpose flour 2 tablespoons tomato paste 1 3/4 cups low-sodium beef broth 2 cups fresh corn, sliced off the cob (you can substitute frozen, thawed corn) Topping: 2 pounds potatoes, peeled and sliced 3/4-inch thick 1 cup shredded sharp Cheddar cheese 1/4 cup sour cream (I like Daisy brand because it doesn't have any additives) 1/2 teaspoon salt 1/4 teaspoon pepper
Adjust oven rack to upper middle position and heat oven to 375 F. Filling: Heat oil in a large skillet over medium heat until shimmering. Add celery, onion and 1/2 teaspoon salt; cook, stirringoccasionally, until softened, 5 to 7 minutes. Stir in garlic, thyme and 1/2 teaspoon pepper; cook until fragrant, about 30 seconds. Add beef, increase heat to medium-high and cook, breaking up any large clumps with a wooden spoon, until no longer pink andbeginning to brown, 6 to 8 minutes. Stir in flour and tomato paste and cook until the tomato paste begins to brown, about 1minute. Stir in the broth, scraping up any browned bits. Bring to a simmer and cook, stirring frequently until the mixture is thick, but still saucy, 15 to 20 minutes. Off the heat, stir in corn and season to taste with salt and pepper. Pourfilling into a broiler-safe 2-quart casserole dish. Topping: While the filling cooks, bring the potatoes and 2 quarts of water to a simmer in a medium saucepan and cook until tender, 20 to 25 minutes. Drain and return the potatoesto the saucepan. Stir over low heat until thoroughly dried, 1 to 2 minutes. Mash the potatoes until smooth, then gently fold in the cheese, sour cream, salt and pepper until the potatoes are thick and creamy. Spread potatoes in an even layer over the filling, making sure to spread them to the very edge of the dish. This will help prevent the filling from bubbling out of the pan. Just incase, place the casserole dish on a foil-lined rimmed baking sheet and bake until the filling is bubbling, about 15 minutes. Turn on the broiler and broil the potato topping until it isgolden brown on top, 3 to 5 minutes. Cool for 10 minutes before serving. Serves 4 to 6.