Lasagna with sautéed mushrooms

For the béchamel sauce:

heat the milk in a small saucepan. Separately, melt the butter in a small frying pan, then add the flour, stirring vigorously with a whisk. As soon as the milk is hot, add a little to the butter and flour roux and stir. Add everything to the milk and stir vigorously over the heat until you obtain a smooth sauce. Remove from the heat, season with salt and pepper and leave to cool.

For the ragù:

Put the oil in a pot with the celery, carrot, and onion, all chopped into small pieces. Sauté and then add the mixed minced meat. Cook over medium heat for 15 minutes. Next, add the tomato purée, season with salt and cook with the lid on for 30-35 minutes over low heat, or until the sauce has thickened. Drain the sautéed mushrooms well and add half to the ragù.

For lasagna:

Take a baking dish and spread a thin layer of béchamel sauce and a layer of ragù. Add the lasagna sheets, then another layer of béchamel sauce and ragù, until all the layers are used up. Finish with a layer of ragù, plenty of grated Parmesan cheese, and a few sautéed mushrooms. Bake at 350°F for 30 minutes (or according to the cooking instructions on the pasta package). Remove from the oven and let rest for a few minutes.