Preheat your oven to 375°F (190°C).
In a large pot, bring water to a boil. Add lasagna noodles and cook according to package instructions until al dente. Drain the noodles in a colander and set aside.
In a mixing bowl, combine ricotta cheese, chopped spinach, half of the mozzarella cheese, Parmesan cheese, egg, minced garlic, salt, pepper, oregano, and basil. Mix well until all ingredients are combined.
In the bottom of the baking dish, spread a thin layer of marinara sauce (about ½ cup). Place 3 lasagna noodles over the sauce.
Spread half of the ricotta mixture over the noodles, followed by a layer of marinara sauce (about ½ cup).
Repeat the layering process: add another 3 lasagna noodles, the remaining ricotta mixture, and another layer of marinara sauce.
Top with the remaining 3 lasagna noodles and cover with the rest of the marinara sauce. Sprinkle the remaining mozzarella cheese on top.
Cover the baking dish with aluminum foil, ensuring that it does not touch the cheese. Bake in the preheated oven for 30 minutes.
After 30 minutes, remove the foil and bake for an additional 15 minutes, or until the cheese is melted and bubbly.
Once cooked, remove from the oven and let it rest for about 10 minutes before slicing and serving.