This white lasagna is layered with homemade pesto, creamy béchamel, crispy pancetta, Mozzarella, and Parmesan for a cozy, savory, cheesy dish. It's a huge crowd pleaser and has become one of my go-to dinner party meals!
Place the basil in the bowl of a food processor. Pulse it a few times to break up the leaves. Add the pine nuts, garlic, and Parmesan and run the food processor until everything is finely minced. Scrape down the sides of the bowl with a rubber spatula every once in a while to ensure the mixture is evenly minced.
While the food processor is running, slowly drizzle the olive oil into the basil mixture until you have a smooth and emulsified pesto sauce.
Add the salt and black pepper. Pulse a few times to incorporate. Taste and season with more salt, if desired.
In a large pan, melt the butter over medium heat. Add the shallots and sauté until they are soft, 3-4 minutes.
Stir in the flour. Whisk the roux for about 2 minutes to cook off the raw flour taste.
Slowly whisk in the milk until the sauce is smooth. Stir constantly until the béchamel is thick and coats the back of a spoon, about 7-8 minutes. Do not let the sauce come to a full boil. Remove it from the heat and set aside.
Preheat the oven to 400°F. Grease a deep 9x13 baking dish. Add the shredded Mozzarella and Parmesan cheeses to a medium bowl and toss to combine. Set aside.
Meanwhile, bring a large pot of heavily salted water to a boil. Cook the lasagna noodles 1-2 minutes less than al dente (the noodles will continue to cook during baking). Drain and set aside.
Line a plate with paper towels. Then, cook the pancetta in a small saucepan over medium-high heat until it is crispy. Using a slotted spoon, scoop the pancetta onto the paper towels. Discard any remaining fat.**
Assemble the Lasagna
Spoon about 1/2 cup of the béchamel on the bottom of the 9x13 pan. Add one layer of noodles, cutting the noodles to fill in any nooks and crannies if necessary.
Top the noodles with a few dollops of the pesto. Use a rubber spatula to spread it evenly across the noodles. Next, spread about 1/2 cup of béchamel over the pesto followed by a sprinkle of pancetta and a handful of the cheese mixture. Repeat this 2-3 more times, finishing with a layer of noodles (make sure to reserve some béchamel and cheese for the top). You should have 3-4 layers total.
Spread the remaining béchamel on the top layer of noodles. Sprinkle the remaining cheese evenly over the top of the sauce.
Bake for 25-30 minutes, until the top is bubbly and browned on the edges, and the internal temperature reaches at least 165°F.
Allow the lasagna to set at room temperature for 10-15 minutes.*** Slice into 12 pieces. Serve and enjoy!
*A note on pesto: if you don't want to make homemade pesto, you can use 2 cups of store-bought pesto instead.**A note on the pancetta: you do not necessarily need to crisp the pancetta. You can add it as-is, but it will cook off some fat and can make the lasagna a bit greasy. If you can't find pancetta, you can also use bacon (preferably unsmoked) or prosciutto.***A note on "setting": the lasagna will need to set for at least 10 minutes after baking to ensure it doesn't fall apart when you cut it.