Heat a tablespoon of olive oil in a skillet over a low/medium heat. Thinly slice the onion. Add the onion to the skillet and cook for a minute to soften. Add the ground almonds and flaked almonds to the skillet with a pinch of salt and pepper. Cook gently for 4-5 minutes or until the almonds are lightly browned and toasted and the onions are crisp at the edges.
Add the grated Parmesan to the skillet. Stir well to combine. Transfer to a bowl and set aside until ready to serve.
Crush the garlic. Heat a tablespoon of olive oil in a medium saucepan and add the garlic. Sweat gently for a minute until tender and fragrant. Add the zucchini, salt, pepper and lemon zest. Stir well to combine and cook for just a few minutes until the zucchini is just tender. Do not overcook, or the zucchini will become too soft.
Roughly chop the olives and basil. Add the olives and basil to the saucepan. Stir through the zucchini spaghetti to combine.
Divide the spaghetti between two serving bowls and drizzle over the remaining tablespoon of olive oil. Crumble the toasted almonds, onion, and Parmesan mixture over the pasta. Serve hot.