Preheat your oven to 375F.
Heat oil in a large non-stick pan over medium heat. Add onions and sauté until softened, about 4-5 minutes. Stir in garlic and cook 1 minute more.
Add in ground beef and continue to cook until it's no longer pink about 5 minutes, breaking it apart with a wooden spoon as it cooks.
Stir in the tomato sauce, Italian seasoning and smoked paprika. Simmer for about 8-10 minutes until the sauce reduces by half, stirring occasionally.
Meanwhile, prepare the zucchini. Cut the ends, then slice them on lengthways into 1/4 inch thick strips.
Add one layer of zucchini slices to a 9-inch oval baking dish (or similar). Top with meat sauce, then a layer of shredded mozzarella.
Repeat the process, finishing with the cheese layer. Sprinkle with ground parmesan cheese and bake for 30-40 minutes, or until hot and bubbly.