Preheat oven to 375F (190C).
Heat a large skillet over medium-high heat and add the ground beef. Cook until browned, breaking it up into small pieces as it cooks.
Add the garlic, leeks, asparagus, mushrooms, tomato paste, oregano, salt, and pepper. Cook for 5 minutes or until the vegetables have softened slightly.
In a 9x13 inch baking dish spread 1/3 of the marinara sauce evenly over the bottom of the pan.
Layer 4 lasagna noodles over top of the marinara sauce, followed by half of the ricotta cheese, half of the ground beef mixture, and 1/3 of the remaining marinara sauce.
Repeat layering with 4 noodles, remaining ricotta cheese, and remaining ground beef mixture. Top with the last 4 noodles, and cover with remaining marinara sauce and mozzarella cheese.
Add a few pieces of asparagus on top for decorative purposes.
Cover baking dish with aluminum foil and bake for 45 minutes.
Uncover baking dish and bake for an additional 15 minutes or until cheese is bubbly and lightly browned.
Let stand 15-20 minutes before serving. Enjoy!