Peel the onions and carrots. Grind them with a knife or using a grater. Thaw minced meat in advance. Grate the cheeses on a fine grater. Wash, peel and finely chop the celery. Prepare a baking dish. Turn the oven on 180 degrees.
Prepare bolognese sauce. Heat oil in a frying pan, add carrots and onions to it. Roast the root vegetables until soft, about 5 to 7 minutes. Then add minced meat and stir. Simmer the sauce base for about 10 minutes. Add the celery 2-3 minutes before it’s ready. Add tomato sauce and Italian herbs. Cover the pan with a lid and simmer for another 15 minutes.
Make bechamel sauce. Melt the butter in a thick-bottomed container. Add flour to it and stir so that there are no lumps left. Gradually add milk without ceasing to stir. Then add salt and nutmeg. As soon as the sauce begins to thicken, turn off the stove.
Make homemade lasagna. Take a baking dish and grease the bottom with a little bechamel sauce. Next, lay out a layer of lasagne sheets. Spread some of the bolognese sauce over it. Then top with the cheese mixture and top with bechamel sauce. Repeat steps until you run out of food. Sprinkle cheese on top of lasagna. Place the mold in an oven preheated to 180 degrees for 40 minutes.
Before serving, let the lasagna with minced meat sit for about 15-20 minutes, then cut into portions and serve.