Preheat and prepare: Set your oven to 200°C (fan-assisted) or 220°C (conventional). While it heats, place a large, deep frying pan or a flameproof casserole dish over a medium-high heat. Add the olive oil and let it shimmer for a moment.

Sweat the aromatics: Add the diced onion to the hot oil. Cook for 5-6 minutes, stirring occasionally, until the pieces turn translucent and soften. You should hear a gentle, steady sizzle—not a frantic crackle. Add the minced garlic and cook for one minute more until it smells fragrant and nutty, not sharp.

Brown the beef: Tip the minced beef into the pan. Break it up with a wooden spoon, then let it sit undisturbed for a couple of minutes. This is key for a good sear. The sound will shift from a wet splatter to a drier, more insistent hiss. Stir and continue cooking until all the meat is a rich, deep brown with no pink remaining. This takes about 6-8 minutes. Drain off any excess fat if necessary, leaving a tablespoon or so for flavour.

Build the sauce: Sprinkle the flour over the cooked beef and stir continuously for one minute. The mixture will look a little claggy and paste-like. Pour in the beef stock in a steady stream, stirring all the while to lift any browned bits from the bottom of the pan. Add the tomato purée, smoked paprika, dried oregano, salt, and pepper. Bring the sauce to a gentle bubble. It should thicken noticeably in 2-3 minutes, turning a glossy, deep mahogany colour.

Add the vegetables and combine: Stir through the frozen peas and sweetcorn. They will cool the mixture slightly, which is fine. Simmer for one more minute, then remove the pan from the heat. The sauce should look rich and hearty, coating the back of a spoon.

Assemble the casserole: Transfer the beef mixture to a 9x13 inch baking dish (if you didn’t use a flameproof one). Spread it into an even layer. Sprinkle half of the grated cheddar cheese evenly over the top. Now, arrange the frozen tater tots in neat rows, standing them on their flat ends if you can. This isn’t fussiness—it ensures every tot gets maximum exposure to the heat, leading to a far superior crunch.

Bake to golden perfection: Place the dish in the preheated oven and bake for 25 minutes. After this time, remove the dish and sprinkle the remaining cheese over the tots. Return to the oven for a final 15-20 minutes. You are looking for the cheese to bubble and brown in patches, and the tater tots to become deep golden and crisp. The sound of the casserole when you pull it out should be a gentle, contented bubbling.

The crucial rest: This is the hardest step. Let the casserole rest on the counter for a full 10 minutes before serving. The filling needs this time to set, so it doesn’t turn into a soupy mess on the plate. The top will stay warm and crisp.