Preheat the oven to 350°F (175°C).
Cook the lasagna noodles in a large pot of boiling salted water according to package directions until al dente. Drain and lay the noodles flat on wax paper or a clean towel to cool.
Steam the fresh spinach until wilted, then chop and squeeze out excess moisture; set aside.
In a large bowl, combine the ricotta, chopped spinach, eggs, grated Parmesan, garlic powder, salt, pepper, and 1 cup of the shredded mozzarella until evenly mixed.
Spread about 1 cup of marinara sauce in the bottom of a 9 x 13-inch baking dish.
Place about 1/4 cup of the ricotta mixture (or enough to cover) onto each noodle and spread into an even layer about 1/4 inch thick. Roll each noodle tightly and place seam-side down in the prepared baking dish.
Spoon additional marinara sauce over the top of each roll, then sprinkle the remaining 1/2 cup shredded mozzarella evenly over the dish.
Bake uncovered for 35–40 minutes, until the cheese is melted and bubbly and the rolls are heated through.
Remove from the oven and let rest a few minutes before serving.
