Preheat the oven to 425F. Place the butternut on a large nonstick baking sheet, spray with oil, season with salt and pepper and bake 15 minutes, turn then cook an additional 10 minutes, or until tender. Let cool a few minutes.
Meanwhile combine the dressing ingredients in a small bowl and whisk.
Divide the lettuce between two plates, top each with half of the remaining ingredients and dressing.