Meatball lasagne

Name: Meatball lasagne
Prep time: 50 min
Total time: 50 min
Cuisine: Italian
Ingredients: 2 tbsp olive oil; 1 large red onion, finely chopped; 500g beef mince (12% fat); 2 tsp dried thyme; 75g Parmesan, grated; 2 medium egg yolks; 4 large garlic cloves, crushed; 175ml red wine; 2 x 500g cartons passata; 1 tbsp caster sugar; 30g butter; 40g plain flour; 500ml milk; 2 bay leaves (fresh or dried); 1 tbsp wholegrain mustard; 1 x 250g pack fresh lasagne sheets; 1 x 250g pack grated mozzarella