Preheat the oven to 350°F (175°C).
Cook the lasagna noodles in a large pot of salted boiling water according to package directions until al dente; drain and lay noodles flat on wax paper or a clean towel to cool.
Steam the fresh spinach until wilted, squeeze out excess moisture, and chop finely.
In a mixing bowl, combine the ricotta, chopped spinach, eggs, grated Parmesan, garlic powder, salt, pepper, and 1 cup of the shredded mozzarella until evenly mixed.
Spoon about 1 cup of marinara sauce into the bottom of a 9 x 13-inch baking dish and spread to cover.
Spread about 2–3 tablespoons (or roughly 1/4 inch thick) of the ricotta mixture over each cooled noodle, then gently roll each noodle and place seam-side down in the prepared baking dish.
Spoon remaining marinara sauce over the rolled noodles and sprinkle the top with the remaining 1/2 cup of shredded mozzarella.
Bake uncovered for 35–40 minutes, until the cheese is melted and bubbly and the edges are heated through.