1: Preheat oven to 425°F. Cut squash into 1 1/2"-thick wedges, leaving skin on. Scrape off seeds and strings with a large spoon and discard. Coat wedges with 3 tablespoons oil and season with salt and pepper. Lay wedges cut side down on a large rimmed baking sheet. Roast, carefully turning halfway through, until golden brown on both sides, about 30 minutes.
2: Heat remaining 1 tablespoon oil in a small skillet over medium-high heat. Add pumpkin seeds and cook, swirling pan often, until seeds are puffed and brown but still have a bit of green, 4-5 minutes. Transfer seeds to paper towels to drain. Sprinkle with salt.
(Squash and toasted pumpkin seeds can be made 4 hours ahead. Let stand separately at room temperature. Rewarm squash before serving.)
3: Transfer squash to a large platter and drizzle with balsamic vinegar. Sprinkle squash with torn mint leaves and toasted pumpkin seeds.