Preheat the oven: Preheat your oven to 400°F (200°C).
Prepare the vegetables: In a large bowl, toss the butternut squash, Brussels sprouts, carrots, and red onion with 2 tablespoons of olive oil, salt, and black pepper.
Roast the vegetables: Spread the vegetables on a baking sheet in a single layer. Roast for 30-35 minutes, tossing halfway through, until tender and caramelized.
Make the dressing: While the vegetables roast, whisk together the balsamic vinegar, Dijon mustard, maple syrup, and the remaining 1 tablespoon of olive oil in a small bowl.
Assemble the salad: Once the vegetables have cooled slightly, toss them with the mixed greens, dried cranberries, and toasted pecans in a large bowl.
Add the dressing: Drizzle the vinaigrette over the salad and gently toss until combined.
Serve: Serve warm or at room temperature.