Heat a frying pan with vegetable oil and fry the crushed garlic until a characteristic aroma appears. Add the onion and bring to softness. Put in the rosemary and bay leaf, then add the tomatoes. Simmer the tomatoes under the lid for 30-35 minutes over medium heat.
Heat a separate frying pan with vegetable oil and fry the mince until golden brown, then pour in the wine. Wait until the wine evaporates, and then simmer under a lid over medium heat for about 15 minutes.
Combine tomato sauce and ready minced meat, mix well. Add tomato paste, salt, pepper and mix again. Simmer under the lid on low heat for about 15 minutes.
Melt the butter in a saucepan, add the flour and mix well. Gradually add the milk, stirring constantly, until the sauce thickens, about 5-7 minutes. Grate the nutmeg.
Boil the lasagne sheets in salted water until al dente.
Grease a baking dish in the oven with olive oil, lay out the lasagne sheets so that they overlap each other, spread the tomato sauce and mozzarella pieces on top. Repeat the layers until you run out of ingredients. On the last lasagne sheets, spread the remaining sauce, pour the béchamel sauce evenly and sprinkle with grated Parmesan.
Place the pan in the oven and bake the lasagne in a preheated oven at 180°C for 40-45 minutes.