-
1
For the white sauce:
-
2
Put the butter and olive oil in a heavy medium saucepan over medium-low heat.
-
3
Stir in the flour and whisk for 3 minutes.
-
4
Stir in in the milk.
-
5
Increase the heat to medium-high.
-
6
Whisk the sauce until it comes to a simmer and is thick and smooth, 2 to 4 minutes.
-
7
Stir in the salt, pepper, and nutmeg into the bechamel sauce.
-
8
Preheat the oven to 450F (230C).
-
9
Combine the ricotta, spinach, 1 cup Parmesan, prosciutto, egg, salt, and pepper in a medium bowl, mix well.
-
10
Add a tablespoon or 2 of oil to a large pot of boiling salted water.
-
11
Boil the noodles until just tender but still firm to bite.
-
12
Drain.
-
13
Place the noodles in a single layer on a baking sheet to prevent them from sticking.
-
14
Grease a 13-by-9-by-2-inch glass baking dish with butter or nonstick cooking spray.
-
15
Pour the bechamel sauce over the bottom of the prepared dish.
-
16
Lay out 4 lasagna noodles on a work surface, then spread about 3 tablespoons of ricotta mixture evenly over each noodle.
-
17
Starting at 1 end, roll each noodle like a jelly roll.
-
18
Lay the lasagna rolls seam side down, without touching, atop the bechamel sauce in the dish.
-
19
Repeat with the remaining noodles and ricotta mixture.
-
20
Spoon 1 cup of marinara sauce over the lasagna rolls.
-
21
Sprinkle the mozzarella and remaining 2 tablespoons of Parmesan over the lasagna rolls.
-
22
Cover tightly with foil.
-
23
Bake until heated through and the sauce bubbles, 18 to 22 minutes.
-
24
Uncover and bake until the cheese on top becomes golden, about 16 minutes longer.
-
25
Take it out of the oven and let stand for 10 minutes.
-
26
As the casserole cools down, heat the remaining marinara sauce in a small heavy saucepan over medium heat until hot, and serve with lasagna alongside.
