Preheat the oven to 200 degrees C/390 degrees F.
Cook the butternut squash in a large pot of well-salted boiling water until easily pierced with a knife, 15 minutes. Drain and set aside to steam dry slightly.
In a bowl, gently toss the boiled squash with the honey, 1 tablespoon olive oil, cinnamon and a good pinch of salt and pepper. Transfer to a nonstick baking sheet.
Roast until lightly golden and crispy on the outside but still fluffy on the inside, 20 minutes. Remove and set aside to cool.
While the squash is roasting, lightly toast the mixed nuts in a dry pan until golden and fragrant.
To serve, lay the salad leaves on a serving platter, then layer over the squash, goat cheese and toasted nuts. Drizzle with the remaining 1 tablespoon olive oil and the balsamic just before serving.