Making the ragù:
- Mise en place is your friend! Prep the following ingredients: 1) Dice the unsmoked pancetta into small cubes (around ½ cm). 2) Finely chop the sweet onion, carrots and celery stalks. 3) Thinly slice the garlic cloves. 4) Remove the rosemary leaves from their stems, leaving them whole. 5) Measure out the white wine. 6) Carefully pour the tinned tomatoes into a medium bowl and crush the tomatoes with your hands. 7) Measure out the chicken stock. 8) Measure out the milk.
- Heat 1 tbsp extra-virgin olive oil in a large Dutch oven over medium heat. Add the unsmoked pancetta and cook, stirring occasionally, until the fat has rendered out and the pancetta is browned and beginning to crisp, around 8 minutes.
- Add the onion, carrots and celery stalks and cook, stirring occasionally, until nice and soft, 10 to 12 minutes.
- Add the garlic and cook for 1 minute, stirring constantly. Add the fresh rosemary leaves and cook for another minute, stirring constantly.
- Turn the heat up to medium-high and add the beef mince, breaking it up with a wooden spoon or potato masher (it works surprisingly well!). Cook until browned, 3 to 4 minutes.
- Add the tomato purée and sundried tomato paste and cook, stirring constantly, until they begin to darken, around 2 mins. Season the meat mixture with ¾ tsp salt and ¼ tsp freshly-ground black pepper
- Add the white wine and cook, stirring occasionally, until it is reduced by around ¾, 7 to 8 minutes.
- Add the crushed tinned tomatoes, chicken stock and milk and bring to a simmer. Reduce the heat to low and cover, leaving the lid slightly ajar. Simmer gently, stirring occasionally, until the meat is very tender and the sauce has thickened, 1 ½ to 2 hours. Taste and season with sea salt and freshly-ground black pepper.
MAKE AHEAD: the ragù can be made up to 3 days ahead; cool, transfer to airtight containers and refrigerate. Alternatively, it can be stored in the freezer for up to 2 months; thaw completely before use.
Making the béchamel:
- Gently bring the milk to a bare simmer in a large saucepan over medium heat. Once it begins to bubble, remove the saucepan from the heat.
- Melt the butter in a large stockpot or saucepan over medium heat. Whisk in the flour and cook for 3 mins, whisking continuously.
- Quickly but carefully whisk in the warm milk and increase the heat to medium-high. Bring to a simmer, whisking often. The béchamel will begin to thicken. Once it barely starts bubbling—a few small bubbles coming up to the surface—reduce the heat to medium-low and cook until thick and velvety-smooth, around 5 mins.
- Remove from the heat and whisk in the Parmigiano Reggiano, 1 ½ tsp sea salt, ½ tsp freshly-ground black pepper and a pinch of nutmeg.
MAKE AHEAD: the béchamel can be prepared the day before; cool, cover and refrigerate. Gently reheat in a saucepan to loosen before use.
Assembling the lasagna:
- Heat oven to 200°C/fan 180°C. Lightly oil a deep 35 cm x 25 cm baking dish.
- Spread 2 ½ cups ragù onto the base of the dish. Cover with a single layer of lasagna sheets; you will likely need to cut some of the sheets to fill all the gaps. Spoon 1 ¼ cup béchamel over the lasagna sheets, spreading it in a thin, even layer with a spatula.
- Repeat the layers—ragù, lasagna sheets, béchamel—until you get to the top of the dish; 5 or 6 layers depending on how deep your dish is. Fill the dish right up to the top; the top pasta-béchamel layer will get nice and crunchy when baked.
- Place the lasagna on an oven tray (to catch spills) and bake for 45 mins or until the pasta is cooked through and the top is browned and crisp around the edges. Let it rest for around 10 mins before serving
NOTES: most recipes call for blanching the lasagna sheets before baking; this one does not (it’s such a faff!). We get round it by making the ragù a little looser than usual - the extra liquid ensures that the pasta cooks perfectly in the oven while the lasagna is baking.
STORAGE: the lasagna can be stored in the fridge for up to 4 days; cool, place in an airtight container and refrigerate—to reheat, heat in microwave on high until piping hot. The lasagna can also be stored in the freezer for up to 1 month, either baked or unbaked. Baked: cool, place in airtight, freezer-safe containers and freeze; to reheat, thaw in the fridge overnight then reheat in the microwave or oven. Unbaked: assemble the lasagna, cool, cover and freeze; to bake, thaw in the fridge overnight then bake for 1 hr at 200 degrees Celsius (fan 180 degrees Celsius) or until the pasta is cooked through the top is browned and crisp around the edges.