Preheat the oven to 375˚F. Bring a large pot of lightly seasoned water to a boil. Add lasagna noodles and cook until al dente, about 8 minutes.

While the pasta cooks, make the filling. Drain the cooked spinach thoroughly, extracting as much excess water as possible. Place drained spinach in a medium bowl and add ricotta, Parmesan cheese, egg, garlic, basil, Italian seasoning, salt, pepper and crushed red pepper flakes. Mix with a fork to combine, making sure to break up any large chunks of spinach so it’s evenly distributed.

Add about ½ cup of marinara sauce to the bottom of a 9 by 13-inch baking dish and spread into an even layer. Set aside.

When the pasta is al dente, drain and set aside in a colander. Working quickly, place one lasagna noodle on a clean work surface. Spread about 2 to 3 tablespoons of prepared ricotta filling evenly all over the surface of the noodle, then roll into a spiral. Place in the baking pan on top of the marinara. Repeat this process with all of the noodles and filing. You should wind up with 4 rows of 3 lasagna roll ups in your baking pan.

Drizzle the remaining marinara sauce on top of the lasagna roll-ups, then sprinkle with mozzarella cheese. Cover the pan tightly with foil and bake for 35 minutes.

Uncover the pan, then bake for an additional 5 minutes or until the cheese is very melty and bubbly.