4. If necessary, boil the lasagna noodles following the instructions on the packaging, start preheating your oven to 175°C/350°F.
5. Spread a thin layer of pasta sauce on the bottom of a large, deep baking tray.
6. Cover with lasagna sheets and spread a layer of béchamel sauce or ricotta, cover with lasagna sheets and spread a layer of pasta sauce if you want you can finely grate a little bit of parmesan on each layer of bolognese.
7. Rinse and repeat the previous step until the tray is nearly full or you are running low on béchamel sauce/ricotta filling, take care that the last layer should be bechamel or ricotta.