This family-friendly dish turns cottage pie on its head. Instead of capping the saucy mixture of simmered meat and vegetables with mashed potatoes, the filling becomes the topper for baked potato boats.
Pierce the potatoes with a fork in a few spots. Put on a microwave-safe plate and microwave until tender, 14 to 16 minutes.
Meanwhile, melt 1 tablespoon butter in a large skillet over medium-high heat. Add the garlic, onion, thyme and 1/4 teaspoon salt. Cook, stirring, until the onion is soft, about 4 minutes. Add the beef, 1/2 teaspoon salt and a few grinds of pepper and cook, breaking up the meat, until no longer pink, about 4 minutes.
Stir in the beef broth, ketchup and Worcestershire sauce and bring to a gentle simmer. Cook, stirring occasionally, until slightly thickened, 6 to 8 minutes. Stir in the peas and carrots and warm through, about 1 minute; season with salt and pepper.
Preheat the broiler. Halve the potatoes lengthwise and fluff the flesh with a fork; top each potato half with 1/2 tablespoon butter and season with salt and pepper. Place on a baking sheet. Divide the meat mixture among the potato halves, then top with the cheese. Broil until melted, about 2 minutes.