Preheat your oven to 375°F (190°C).
In a skillet over medium heat, brown the pork sausage until fully cooked and no longer pink, then drain any excess fat.
Boil the brown rice lasagna noodles according to the package instructions until al dente, drain, and set aside.
In a small bowl, whisk the half egg and combine it with the ricotta cheese, dried oregano, garlic powder, sea salt, and black pepper.
In a small individual-sized baking dish, spread a thin layer of marinara sauce on the bottom.
Layer half of the lasagna noodles (broken to fit), followed by half of the cooked sausage, half of the fresh spinach, and the ricotta mixture.
Repeat the layers with the remaining noodles, sausage, and spinach, then top with the remaining marinara sauce and shredded mozzarella.
Cover the dish with foil and bake for 20 minutes.
Remove the foil and bake for an additional 5 to 10 minutes until the cheese is bubbly and lightly golden.