- 3 pounds new potatoes (about 30)
- kosher salt and black pepper
- 1 cup whole milk
- 4 tablespoons unsalted butter
- 2 tablespoons olive oil
- 1 pound frozen pearl onions, thawed
- 1 1/2 pounds ground beef chuck
- 1/4 cup tomato paste
- 1 tablespoon Worcestershire sauce
- 1/4 cup all-purpose flour
- 2 cups low-sodium chicken broth
- 1 medium butternut squash (about 2 pounds), peeled and cut into 3/4-inch pieces
- 1 cup frozen peas
- Heat oven to 350° F. Place the potatoes in a large pot, add enough cold water to cover by 1 inch, and bring to a boil. Add 1 teaspoon salt, reduce heat, and simmer until tender, 15 to 18 minutes. Drain and return the potatoes to the pot; add the milk, butter, ½ teaspoon salt, and ¼ teaspoon pepper and mash.
- Meanwhile, heat 1 tablespoon of the oil in a 5- to 6-quart Dutch oven over medium-high heat. Add the onions and cook, stirring often, until beginning to soften, 4 to 6 minutes; transfer to a medium bowl.
- Heat the remaining tablespoon of oil in the Dutch oven. Add the beef, ½ teaspoon salt, and ¼ teaspoon pepper and cook, breaking the beef up with a spoon, until no longer pink, 4 to 6 minutes; mix in the tomato paste and Worcestershire sauce. Sprinkle with the flour and cook, stirring, for 1 minute. Add the broth, squash, peas, and onions and bring to a simmer.
- Transfer the beef mixture to a 9-by-13-inch or some other 3-quart baking dish and top with the potatoes.
- Bake until the potatoes are lightly golden, the filling is bubbling, and the squash is tender, 40 to 45 minutes. Let cool for 5 minutes before serving.