Boil potatoes: Start by placing the cubed potatoes in a large pot of salted water. Boil them until they are tender, roughly 15-20 minutes. Drain and set aside.

Mash potatoes: In the same pot, add butter, milk, salt, and black pepper to the drained potatoes. Mash until smooth and creamy, tasting and adjusting the seasoning as needed.

Sauté aromatics: In a large skillet over medium heat, add a drizzle of oil and sauté the diced onion and minced garlic until softened and fragrant, about 5 minutes.

Brown the beef: Add the ground beef to the skillet, using a spatula to break it apart. Cook until browned and no longer pink, about 6-8 minutes. Drain any excess fat from the skillet.

Build the filling: Stir in the tomato paste, paprika, cumin, chili flakes (if using), beef broth, and Worcestershire-style seasoning. Let it simmer for about 10 minutes until the mixture thickens and becomes aromatic.

Assemble and bake: Preheat your oven to 400°F (200°C). Spread the beef mixture evenly in a baking dish and top it generously with the creamy mashed potatoes. Bake for 20-25 minutes or until the top is golden and bubbling.