Build the flavour base: Heat the olive oil in a large, heavy-based pot or Dutch oven over a medium heat until it shimmers and smells fragrant. Add the diced onion and cook for 6-8 minutes, stirring occasionally, until it turns translucent and softens — you'll know it's ready when the kitchen smells sweet and the onions look glassy, not brown.

Brown the beef properly: Increase the heat to medium-high and add the beef mince. Break it up with a wooden spoon and let it sit undisturbed for 2 minutes to develop a deep, dark crust on one side. The sizzling sound will be vigorous. Stir and repeat until all the meat is browned and no pink remains — the colour should be a rich mahogany, and the smell will shift to something deeply savoury.

Add the aromatics and vegetables: Stir in the minced garlic and grated carrots. Cook for 2 minutes until the garlic is fragrant — be careful not to burn it, the scent should be pungent but not acrid. The carrots will soften and release a touch of moisture.

Build the marinara: Add the tomato purée and stir for 1 minute — it will darken slightly and stick to the bottom of the pan, which is good. Pour in the chopped tomatoes, oregano, basil, and the bay leaf. Season with a good pinch of salt and a few cracks of black pepper. Bring the sauce to a gentle bubble — you'll see lazy bubbles breaking the surface, not a violent boil — then reduce the heat to low. Let it simmer uncovered for 20 minutes, stirring every now and again. The sauce will thicken and deepen in colour, and the aroma will fill your kitchen with a rich, tangy sweetness.

Cook the tortellini: While the sauce simmers, bring a large pot of salted water to a rolling boil. Add the tortellini and cook for 3-4 minutes (or according to package directions) until they float to the surface and are just tender — they should still have a slight resistance when bitten. Drain them, reserving about 100ml of the pasta water. Do not rinse them; the starch helps the sauce cling.

Combine and layer: Preheat your oven to 190°C (170°C fan). Remove the bay leaf from the sauce. Stir in the cooked tortellini and the reserved pasta water — the water loosens the sauce just enough to coat every pocket of pasta. Taste and adjust the seasoning. Pour half the mixture into a 9x13 inch baking dish. Sprinkle with half the mozzarella and parmesan. Add the remaining tortellini mixture and top with the rest of both cheeses. The surface should look uneven and textured, not flat — those peaks and valleys will brown beautifully.

Bake until golden and bubbling: Place the dish on the middle rack and bake uncovered for 25-30 minutes. Check at 20 minutes — you're looking for a deep golden-brown crust on top, with the sauce visibly bubbling around the edges. The mozzarella should be melted and slightly blistered in spots. Remove from the oven and let it rest for 5-8 minutes — the dish needs this time to settle, or it will be too loose when served.