Preheat your oven to 400°F and line a baking sheet with parchment paper.
In a large mixing bowl, mash the cooked lentils lightly with a fork or potato masher, leaving some texture.
Stir in the rolled oats, egg, and Parmesan cheese until well combined.
Add garlic powder, dried oregano, dried basil, salt, and pepper. Mix thoroughly to distribute the spices evenly.
Form the mixture into small meatballs, about 1 to 1.5 inches in diameter, and place them on the prepared baking sheet.
Bake in the oven for 18-20 minutes until they are firm and lightly golden, turning once halfway through.
While the meatballs are baking, warm the marinara sauce in a small saucepan over low heat. Optionally, add a dash of salt and pepper.
Once the meatballs are done, gently spoon the warm marinara sauce over them or serve it on the side for dipping.
Plate the meatballs and enjoy a hearty, flavorful meal that's perfect for breakfast, lunch, or dinner.