In a large skillet, heat the olive oil over medium heat and add the garlic and onions. Cook the onions and then add the ground beef and marinara sauce.
Use a sharp knife to cut the end and top off the zucchini so it can easily stand up straight. Use a y-shaped peeler to slice very thin ribbons from the zucchini by peeling along the long side.
In a small bowl, quickly stir together the ricotta cheese, lemon juice, and oregano. Spoon about a tablespoon of the cheese onto the ends of a zucchini ribbon laying on a flat surface.
Use your hands to gently roll up the cheese into the zucchini. This doesn't have to be super tight but you do want the cheese to be secure inside the zucchini.
Use a spoon or your spatula to create little holes in the red sauce and place a roll up into each throughout the skillet or baking dish.
Grate some fresh parmesan cheese over top of the dish and bake it in the oven until the zucchini are slightly crispy and have turned a golden color on top.