Preheat the oven to 425°F.
Cut the squash in half lengthwise and remove any pulp and seeds.
Slice the squash into 1 1/2-inch wedges.
Toss the squash on a rimmed baking sheet with olive oil, maple syrup, paprika, red-pepper flakes, and a sprinkle of kosher salt and black pepper.
Roast in the oven for 40 to 45 minutes, turning once, until browned and tender.
In a small skillet, toast hazelnuts over medium heat for 4 to 6 minutes until browned and fragrant.
Transfer the roasted squash to a serving platter.
Drizzle with more olive oil and maple syrup.
Sprinkle with toasted hazelnuts, flaky sea salt, and black pepper.
Zest and squeeze the lemon juice over the dish before serving.