Heat the oil in a large saucepan. Add the onion and cook over medium heat for 3 mins, stirring occasionally, until softened.

Add the garlic and cook for 1 min, then tip in the mince and cook, stirring and breaking it up with a wooden spoon, for about 6 mins until browned all over.

Stir in the tomato purée and cook for 1 min, mixing in well with the beef. Tip in the pasta sauce. Add salt, pepper and basil leaves, stir to mix. Simmer with the lid on for 20 mins.

Make the bechamel sauce. Gently bring 500ml whole milk to the boil in a small saucepan with 1 halved onion, studded with 1 bay leaf and 2 cloves. Turn off the heat and leave to infuse for 20 mins.

Melt 50g butter in another saucepan, then add 50g plain flour. Stir continuously until a paste form – this is called a roux. Continue cooking for 2 mins.

Remove the onion, bay and cloves from the milk with a slotted spoon and discard. Add the infused milk to the roux gradually, stirring as you go, until you get a smooth sauce. Cook for 5-10 mins, stirring continuously until the sauce has thickened. Season to taste.

Heat oven to 180C fan. To assemble the lasagne, ladle a little of the sauce into the bottom of the casserole dish, spreading the sauce all over the base. Place a few sheets of lasagne on top of the sauce overlapping to make it fit, then spread white sauce, top with drops of ricotta cheese. Repeat with a further 3 layers of sauce, pasta, bechamel and ricotta, finishing with a layer of pasta.