Finely dice the onion, carrot, celery, and garlic. The vegetables should be very small — roughly the size of coarse crumbs. This fine texture allows them to melt into the sauce during the long braise and creates the traditional base known as soffritto.

Heat a large heavy Dutch oven over medium heat. Add the olive oil and diced pancetta. Cook for 6–8 minutes until the fat renders and the pancetta begins to turn lightly golden.

Add the diced onion, carrot, celery, and garlic to the pot. Season lightly with salt. Cook slowly for 12–15 minutes, stirring occasionally, until the vegetables soften and begin to caramelize. The bottom of the pot should develop browned bits (fond), which add depth to the sauce.

In a separate large skillet, cook the ground beef and veal over medium-high heat. Break the meat apart and cook until all moisture evaporates and the meat develops deep browning. This should take 10–12 minutes. Proper browning is essential for a rich ragù.

Transfer the browned meat to the pot with the soffritto. Stir and cook for 3–4 minutes so the flavors integrate and additional fond develops.

Add the tomato paste and cook for 3–5 minutes, stirring frequently. The paste should darken slightly and develop a deeper flavor.

Pour in the red wine and scrape the bottom of the pot to dissolve the browned bits. Let the wine reduce until nearly syrupy, about 5–7 minutes.

Pour in the beef stock and whole milk. Stir well and bring the mixture to a gentle simmer.

Transfer the pot (uncovered) to a 175°C oven and cook for 3 hours, stirring every 30–40 minutes. The sauce should slowly thicken, darken, and develop a deep, rich flavor.

Remove the pot from the oven. Stir in the butter and grated Parmigiano Reggiano until melted. Taste and adjust seasoning with salt if needed. Allow the sauce to cool slightly before assembling the lasagne.

In a bowl combine ricotta, egg, salt, and black pepper. Whisk until smooth and creamy.

In another bowl combine the grated mozzarella and Parmesan cheese.

Bring a large pot of salted water to a boil. Cook the pasta sheets 1 minute less than package instructions. Drain and place them on a lightly oiled baking sheet to prevent sticking.

Preheat the oven to 190°C. Spread about 250 ml ragù across the bottom of a 23 × 33 cm baking dish. Add a layer of lasagna sheets. Spread ⅓ of the ricotta mixture, then sprinkle ⅓ of the cheese mixture, followed by another layer of ragù.

Repeat the layering process two more times: pasta → ricotta → cheese → ragù. Finish with a final layer of pasta, a thin layer of sauce, and the remaining cheese.

Cover the dish with foil (lightly greased on the underside). Bake for 25 minutes. Remove the foil and continue baking for 30–35 minutes until the top is bubbling and golden.

Allow the lasagne to rest 15–20 minutes before slicing. This helps the layers set and prevents the dish from collapsing when cut.