Preheat your oven to 375°F (190°C).
Cook the whole wheat lasagna noodles in a pot of boiling salted water until al dente, then drain and set aside.
In a skillet over medium heat, add the olive oil and minced garlic, sautéing for 1 minute until fragrant.
Add the ground beef to the skillet, seasoning with sea salt, black pepper, and dried oregano; cook until fully browned.
Toss the fresh baby spinach into the skillet with the beef and stir until just wilted, then remove from heat.
In a small bowl, stir the ricotta cheese with a pinch of black pepper to combine.
Spread 2 tablespoons of marinara sauce on the bottom of a small individual-sized baking dish.
Begin layering by placing a portion of the noodles on the sauce, followed by a layer of the beef and spinach mixture, a dollop of ricotta, and more marinara.
Repeat the layers until all ingredients are used, finishing with the mozzarella cheese on top.
Cover the dish with foil and bake for 20 minutes, then remove the foil and bake for an additional 10 minutes until the cheese is melted and golden.