Cook pasta according to package instructions in a large pot of boiling salted water then drain well.
To make the sauce, blitz together the avocados, basil, garlic and lemon juice in a food processor until smooth.
Season to taste. With the motor running, slowly pour in the olive oil until emulsified.
To serve, combine the pasta, avocado sauce, cherry tomatoes and grated courgette. Toss well and squeeze over a little more lemon juice and sprinkle with the zest.
Serve immediately.