Cook the pasta according to the packet instructions.
In a frying pan, heat the butter over a gentle heat. Add the garlic and the lemon zest and let sizzle in the pan for a few seconds. Add the courgette to the pan and quickly toss in the butter - you don't want to overcook it!
Stir in the mascarpone, parmesan, lemon juice and basil until combined.
Drain the pasta, reserving 1/4 cup of the cooking water. Tip the drained pasta into the sauce and toss to coat. Add as much of the reserved pasta water as desired until the pasta is well-coated and saucy. Season to taste with salt and pepper.
If liked, toast some breadcrumbs in butter (1 tablespoon butter to 1/2 cup breadcrumbs) and sprinkle over the top of the pasta. Finish with shaved parmesan.