Ingredients

Step by step

1. Preheat the oven to 200°C, fan 180°C, gas 6. Heat 1 tablespoon of oil in a large, deep frying pan and fry the onion with a pinch of salt on a low heat until tender (about 10 minutes), then tip into a large bowl and allow to cool slightly. Add the mince, thyme, 50g Parmesan and the egg yolks. Season with salt and a generous amount of pepper and mix together with your hands. Roll the mixture into about 30 small balls (this is easiest with damp hands).
2. Heat the rest of the oil in the pan and brown the meatballs all over, in 2 batches. Remove from the pan with a slotted spoon and set aside. Add the garlic and fry, stirring, for a minute or so until aromatic. Pour in the wine, increase the heat to high and boil for a couple of minutes to reduce, scraping the sticky goodness up off the bottom of the pan. Add the passata and sugar. Bring to the boil, then simmer for 40 minutes until thickened; season and remove from the heat. Set aside 12 of the meatballs (for the top) and stir the rest into the sauce.
3. Meanwhile, make the white sauce. Place the butter and flour in a medium saucepan and heat gently, stirring, until the butter has melted and the flour is incorporated. Continue to stir over a low heat for 2-3 minutes, until the flour is golden brown. Whisk in the milk a splash at a time, until you have a smooth sauce. Add the bay leaves and bring to the boil, stirring. Simmer for 2 minutes, then remove from the heat. Add the mustard and remaining Parmesan, stir until melted and season to taste.
4. To assemble the lasagne, arrange half the meatballs in sauce in a 30 x 20cm baking dish. Top with half the lasagne sheets, tearing them to fit. Spoon over half the white sauce, removing the bay leaves, and top with one third of the mozzarella. Repeat these layers once more. Arrange the reserved meatballs on the top and scatter with the remaining mozzarella. Bake for 30 minutes, until golden. Allow to rest for 5-10 minutes before serving.
5. Watch this...

   Meatball lasagne