Start prepping this side the day before, then finish it off in the morning.
Arrange a rack in the center of the oven; preheat to 400°. Line a large rimmed baking sheet with parchment paper. Arrange the squash, cut-side up, on the baking sheet. Drizzle with 1 tbsp. oil. Dot with the butter; season with salt and pepper. Roast the squash, brushing once or twice with the juices on the baking sheet during cooking, until tender and golden brown in spots, about 1 hour, 5 minutes to 1 hour, 10 minutes.
Meanwhile, in a small saucepan, heat the garlic, a pinch of salt, and the remaining oil over low, stirring often, until the garlic is very tender, 18 to 20 minutes. Remove from heat. Let cool for 5 minutes. Stir in the chives, parsley, and crushed red pepper; season with salt.
Transfer the squash to a platter. Top with the garlic-herb oil.
Up to 1 Day Ahead: Bake the squash. Let cool, then cover and refrigerate.
8 Hours Ahead: Make the garlic-herb oil. Let cool completely, then cover and refrigerate.
20 Minutes Before Serving: Tent the squash with foil. Warm in a 350° oven until heated through, about 20 minutes. Reheat the garlic-herb oil.
Thanksgiving recipes for planners and procrastinators here.