Preheat oven to 375°F (190°C).

In a medium pot over medium heat, combine crushed tomatoes and minced garlic. Simmer for about 10 minutes.

In a large bowl, sprinkle kosher salt over fresh spinach and squeeze until wilted. Let sit for 5 minutes before squeezing out excess moisture.

Mix the wilted spinach with ricotta, mozzarella, Parmesan, egg, black pepper, and nutmeg in the same bowl until well combined.

Cook lasagna noodles according to package instructions until just shy of al dente; drain and cool.

Spread tomato sauce evenly in a baking dish. Lay noodles flat and spread filling over each noodle, then roll tightly into pinwheels.

Place pinwheels in the baking dish seam-side down; top with remaining sauce and cover with foil.

Bake covered for 25 minutes; uncover and bake an additional 5 minutes until golden.