Heat the olive oil in a large oven-safe skillet over medium-high heat. Once shimmering, add the ground beef and break it up with a spoon, cooking for 3-4 minutes until it starts to brown. Add the diced onion, minced garlic, 1.5 teaspoons of salt, smoked paprika, and pepper. Continue cooking for another 3-4 minutes, stirring occasionally, until the beef is fully browned and the aromatics are fragrant. I like to use smoked paprika here because it adds a depth that regular paprika just can't match—it's worth seeking out. Once cooked, transfer the beef mixture to a plate and set aside.

While the beef cooks, preheat your oven to 375°F. Cut the potatoes into 1-inch chunks—this size is important because they'll cook through evenly without getting mushy on the outside. I always cut potatoes this size for one-pan dishes so you don't end up with some pieces falling apart while others stay hard.

In the same skillet (don't wash it—those browned bits add flavor), add the potato chunks and 1 teaspoon of salt. Stir to coat with the remaining oil and browned bits from the beef. Add 1.25 cups of water, cover the pan with a lid or foil, and cook over medium heat for 15-20 minutes, stirring halfway through. The potatoes are done when a fork easily pierces the largest piece. This steaming step ensures the potatoes are tender before we add the cheese and bake.

Return the cooked beef mixture from Step 1 to the skillet. Stir in the mustard, Worcestershire sauce, and ketchup, mixing until everything is evenly combined. The Worcestershire and mustard work together to deepen the savory notes, while the ketchup adds just enough sweetness to balance everything. This is where the dish really comes together—all those flavors are now mingling with the potatoes.

Stir in half of the shredded cheddar cheese (1 cup) until melted and distributed throughout the dish. Spread the remaining cheese evenly over the top. Place the skillet in the preheated 375°F oven and bake for 5 minutes, just until the cheese on top is melted and lightly golden. Don't overbake—you want that cheese creamy, not browned.

Remove the skillet from the oven and let it rest for 1-2 minutes. Sprinkle the fresh chopped parsley over the top for color and brightness, which cuts through the richness of the cheese and beef. Serve directly from the skillet while hot.