Heat olive oil in a medium saucepan over medium heat. Add diced onion and sauté until translucent for about 5 minutes. Stir in minced garlic and cook for 1 minute. Add crushed tomatoes, dried basil, dried oregano, salt, and pepper. Simmer for 20 minutes, stirring occasionally until thickened.

In a large pot, bring water to a boil and add a pinch of salt. Cook lasagna noodles according to package instructions until al dente, about 8-10 minutes. Drain well and lay flat to cool.

In a mixing bowl, combine thawed spinach, ricotta cheese, shredded mozzarella cheese, Parmesan cheese, and a beaten egg. Mix thoroughly until well combined.

Spread spinach filling over each lasagna noodle. Roll from one end to the other and place seam side down in a greased baking dish. Repeat until all noodles are rolled.

Pour the remaining tomato sauce over the roll-ups and sprinkle with additional shredded mozzarella cheese. Preheat oven to 375°F and bake for 25 minutes until cheese is bubbling and golden.