Put a large pot of water on to boil. Once boiling, add salt until it 'tastes like the sea' then add the pasta.
Slice the zucchini into batons or matchsticks.
Use a microplane grater to grate the lemon zest. Then squeeze the juice and set aside.
Place a large skillet over medium low heat. Add the olive oil and once it's shimmering, add the zucchini to the pan and season with salt. Cook the zucchini until just softened and still bright green, don't let it take on any color.
When the pasta is just shy of al dente, use tongs to transfer it directly into the skillet with the zucchini. Scoop out about ½ cup of the pasta water and add to the skillet, turn the heat up to medium. Stir in the mascarpone until completely melted.
Add the parmesan cheese, continue stirring until it melts into the sauce that's forming with the pasta water and mascarpone. When some of the pasta water has been absorbed, all cheese is melted and the sauce has gotten creamy, stir in the butter.
Remove from heat and stir in the lemon juice and zest. Transfer to serving dishes and top with fresh basil, and more lemon zest if desired.
