Cook the Potatoes: Place potatoes in a large pot of salted water. Bring to a boil and cook until fork-tender, 15-20 minutes. Drain well, mash with butter and milk until smooth, then season with salt, pepper, and cheddar cheese. Set aside.
Prepare the Meat Mixture: Heat olive oil in a large skillet over medium heat. Add onion and cook until softened, 4–5 minutes. Stir in garlic and cook 1 minute more.
Add ground beef and cook until browned, breaking it up with a spoon. Drain excess fat if needed. Sprinkle flour over the meat, stir well, and cook for 1–2 minutes. Add tomato paste, Worcestershire sauce, rosemary, thyme, salt, and pepper. Stir in broth, carrots, and peas. Simmer gently for 15 minutes until thickened.
Assemble the Pie: Preheat oven to 400°F (200°C). Spread the meat mixture evenly in a 13×9-inch (33x22cm) baking dish. Spoon the mashed potatoes on top and smooth with a spatula. Create texture with a fork for crisp edges.
Bake: Bake uncovered for 25–30 minutes, until golden and bubbling. Let rest 10 minutes before serving.
Notes
Cheese Options: Use sharp cheddar, parmesan, or even gruyère for extra flavor.
Vegetable Swaps: Replace peas and carrots with corn, celery, or green beans.
Meat Alternatives: Try ground lamb (traditional shepherd’s pie), ground turkey, or even a plant-based mince.
Make Ahead: Assemble the pie a day in advance, cover, and refrigerate. Bake just before serving.
Freezing: Cottage pie freezes well. Wrap tightly and freeze up to 3 months. Reheat from frozen at 350°F (175°C) until heated through.
Extra Creamy Potatoes: Add more butter or cream in place of milk for a richer mash.
Gluten-Free Option: Skip the flour and thicken the filling with 1 tablespoon cornstarch mixed into cold broth.
Storage: Leftovers keep 3–4 days in the fridge. Reheat in the oven for best results.