Cook the pasta in lightly salted boiling water for 10 minutes or until just cooked. Add the beans and squash for the final 2 minutes of cooking time.
Meanwhile, heat the oil in a large frying pan, add the beetroot and cook, stirring occasionally, for 10 minutes until cooked but still firm.
Toss the drained pasta mixture with the beetroot, walnuts and goats' cheese. Squeeze over the lemon juice and serve immediately with a bowl of Parmesan, if liked.