Preheat the oven to 400°F. Toss the cubed butternut squash with 2 tablespoons olive oil, salt, and black pepper on a baking sheet.
Spread the squash in a single layer and roast for 25 minutes, stirring once halfway through, until the edges turn golden and the pieces soften.
While the squash roasts, place the kale in a large bowl. Drizzle with the remaining 1 tablespoon olive oil and massage the leaves for 2 minutes until they darken and soften slightly.
Whisk the balsamic vinegar into the bowl with the kale.
Add the warm roasted squash to the kale and toss gently to combine.
Sprinkle the pumpkin seeds and dried cranberries over the top just before serving.