Shepherd's Pie / Cottage Pie

Heat a large skillet or Dutch oven over medium-high heat. Add the ground beef and cook, breaking it up with a spoon, until browned. Drain off any excess fat. Add the chopped onion, carrots, and celery to the skillet. Cook until softened, about 5-7 minutes. Stir in the minced garlic and cook for 1 minute more until fragrant.

Stir in the beef broth, tomato paste, Worcestershire sauce, and dried thyme. Season with salt and pepper to taste. Bring to a simmer, then reduce heat to low and cook for 10-15 minutes, allowing the sauce to thicken slightly. Stir in the frozen peas during the last 5 minutes of cooking.

While the filling simmers, place the peeled and cubed potatoes in a large pot. Cover with cold water by about an inch. Add a generous pinch of salt. Bring to a boil over high heat, then reduce heat to medium and cook until fork-tender, about 15-20 minutes.

Drain the potatoes thoroughly. Return them to the hot, empty pot. Add the butter and milk. Mash the potatoes until smooth and creamy. Season with salt and pepper to taste.

Preheat your oven to 400°F (200°C).

Pour the meat filling into a 9x13 inch baking dish or individual ramekins. Spread the mashed potatoes evenly over the top of the filling, creating a seal around the edges.

Place the baking dish on a baking sheet (to catch any drips) and bake for 20-25 minutes, or until the topping is golden brown and the filling is bubbly.

Let the Shepherd's Pie rest for at least 5 minutes before serving to allow it to set.