Brown the mince with patience: Melt the butter in a large, heavy-based ovenproof skillet or Dutch oven over a medium-high heat. Add the minced beef, breaking it apart with a wooden spoon. Let it sit undisturbed for a full 2–3 minutes until the underside is a deep mahogany brown—listen for the satisfying sizzle that tells you the pan is hot enough. Stir and repeat until all the meat is evenly browned, about 6–8 minutes total. The kitchen will smell rich and toasty. Use a slotted spoon to transfer the beef to a plate, leaving about a tablespoon of rendered fat in the pan.

Sweat the aromatics: Lower the heat to medium. Add the diced onion to the pan and stir to coat in the fat. Cook for 4–5 minutes, stirring occasionally, until the onions turn translucent and begin to soften. You'll notice their sharp, raw smell mellow into a sweet, gentle fragrance. Add the minced garlic and stir for another 30 seconds until it becomes fragrant—be careful not to let it burn, as burnt garlic turns bitter.

Build the flavour base: Stir in the tomato purée, smoked paprika, onion powder, dried thyme, black pepper, and salt. Cook for 1 minute, stirring constantly. The paste will darken slightly and release a deep, concentrated tomato aroma that clings to the onions. Sprinkle the flour over the mixture and stir well, cooking for another 1–2 minutes until the flour is fully incorporated and smells slightly nutty. This roux is the secret to a luscious, non-lumpy sauce.

Create the creamy sauce: Slowly pour in the beef stock while whisking constantly to prevent lumps. Then add the milk in a steady stream, still whisking. Bring the liquid to a gentle simmer—you'll see small bubbles breaking the surface, but not a rolling boil. The sauce will thicken noticeably after about 3–4 minutes of simmering, turning a warm, burnt-orange colour. Return the browned mince to the pan, along with any juices that have collected on the plate.

Cook the pasta right in the sauce: Stir in the dried pasta, ensuring every piece is submerged in the sauce. Cover the pan with a lid and reduce the heat to low. Let it simmer gently for 12–15 minutes, stirring once halfway through. The sound should be a soft murmur, not a frantic bubble. When the pasta is al dente (tender but with a slight bite), remove the lid. The sauce will have thickened further and coated the pasta generously.

Melt the cheese for a golden finish: Preheat your grill to a high setting. Remove the pan from the hob and stir in 150g of the grated cheddar and all the Parmesan until fully melted. The sauce will become glossy and stretchy. Smooth the top with a spatula, then sprinkle the remaining 50g of cheddar evenly over the surface. Place the pan under the grill for 2–3 minutes, watching closely. You're looking for the cheese to bubble, turn a deep gold, and form a few darker spots—the aroma of toasted cheese will be irresistible.

Rest before serving: Remove the casserole from the grill and let it sit on the counter for at least 5 minutes. This rest time allows the sauce to settle and thicken further, so it clings to the pasta rather than pooling on the plate. Garnish with fresh parsley if desired, and serve straight from the pan for maximum cosy effect.