Knead flour, ½ tsp salt and 260ml water in an electric mixer fitted with a dough hook until dough is very smooth (15 minutes; you may need to add a little more water). Wrap in plastic wrap and set aside to rest (30 minutes).
Divide dough into 5 pieces. Roll each into a cylinder on a lightly floured surface and cut in half, then roll each half into a 1cm-diameter cylinder. Cut each into 1cm pieces and dust lightly with flour. Flatten each piece to form a long oval, then press lengthways along the centre of each piece with a butter knife to create an indent with the sides rolling in towards one another. Transfer cavatelli to a tray lightly dusted with flour and repeat with remaining dough.
For zucchini sauce, heat butter in a saucepan over medium heat, add zucchini in batches and stir occasionally until zucchini is tender, but butter and zucchini are not coloured (5 minutes). Transfer to a bowl with a slotted spoon. Add garlic to pan, cook until translucent (3-4 minutes), return zucchini to pan and keep warm.
Meanwhile, cook pasta in batches in salted boiling water until just cooked (3-4 minutes). Drain, reserving 300ml pasta water, and return pasta to pan with zucchini mixture. Add 100ml reserved pasta water, stir over medium heat (1 minute), then continue adding reserved pasta water 100ml at a time and stir until zucchini is very tender and liquid forms a thick sauce (2-3 minutes; you may not need all the reserved pasta water). Stir in basil and lemon rind, season to taste and serve hot with grated parmesan.
This recipe is from the March 2013 issue of Australian Gourmet Traveller.