1Preheat your oven to 350°F (175°C).
In a large skillet, cook the ground beef over medium heat until browned. Drain any excess fat.
Add the taco seasoning to the cooked beef and stir well to combine.
Cook the rice according to the package instructions.
In a large mixing bowl, combine the cooked rice, marinara sauce, and spinach. Mix well.
Add the seasoned ground beef to the rice mixture and stir until everything is evenly combined.
Transfer the mixture to a greased casserole dish.
Sprinkle the shredded cheese evenly over the top of the casserole.
Bake in the preheated oven for 20-25 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let it cool for a few minutes before serving.