Preheat your oven to 180°C (350°F) and position a rack in the middle of the oven.

Make the ricotta white sauce: into a blender add 500 g fresh ricotta cheese, 2 tablespoons grated vegetarian Italian-style hard cheese (or Parmesan), 220 ml fresh milk, 1 tablespoon extra-virgin olive oil and ⅛ teaspoon grated nutmeg. Blend until smooth and creamy. If the sauce seems too thick to spread, add a little more milk and blend again. Season to taste with sea salt and freshly cracked black pepper. Set the sauce aside.

Sauté the spinach: heat 2 tablespoons extra-virgin olive oil in a large skillet over medium-low heat. Add the finely minced shallot (or red onion) and cook until softened, about 1–2 minutes. Add 300 g fresh (or defrosted) spinach leaves, cover, and cook about 2 minutes. Remove the lid, stir, and cook another 2 minutes until wilted. Remove from the heat, transfer the spinach to a bowl, and press or squeeze out any excess liquid. Set aside.

Prepare the remaining fillings: very well drain the 2 mozzarella balls and thinly slice them; thinly slice the 2 steamed potatoes (peeled); tear or roughly chop the handful of basil leaves. Trim the 8–10 fresh lasagna sheets as needed so they fit your baking dish.

Choose a baking dish that will hold several layers of lasagna sheets. Brush the bottom of the dish with a layer of the ricotta white sauce to prevent sticking.

First layer: place lasagna sheets in a single layer over the sauce to cover the bottom. Spread half of the 1 cup pea pesto evenly over these sheets. Arrange half of the sliced potatoes over the pesto, then half of the sliced mozzarella, and scatter half the basil leaves.

Second layer: cover the first layer with another layer of lasagna sheets. Spread an even layer of the ricotta white sauce over these sheets, then top with the sautéed spinach (spread it evenly).

Third layer: add another layer of lasagna sheets. Spread the remaining pea pesto evenly over these sheets. Arrange the remaining sliced potatoes, remaining sliced mozzarella, and the remaining basil over the pesto.

Top layer: place a final layer of lasagna sheets over the third layer. Spread the remaining ricotta white sauce evenly over the top sheet to create a thick, even white layer (the ricotta sauce is thicker than a classic béchamel, so be generous).

Bake the assembled lasagna uncovered on the middle rack for about 20 minutes, or until the pasta sheets are cooked through and the filling is gently bubbling.

For a browned top, place the lasagna under the oven grill/broiler for about 3–5 minutes, watching carefully to avoid burning.

Remove the baking dish from the oven and let the lasagna rest for 5–10 minutes before slicing and serving.