Preheat your oven to 400°F (200°C) and line a rimmed baking sheet with parchment paper or foil for easier cleanup.
Wash and thoroughly dry the acorn squash. This helps the oil coat evenly and ensures crisp edges.
Carefully cut the squash in half lengthwise, just off-center of the stem. Use a spoon to scrape out the seeds and stringy pulp, creating a clean cavity.
Trim any tough stems from the top and bottom of the squash, then cut each half into 1-inch thick slices.
Place the slices in a large mixing bowl. Drizzle with oil, season with salt, pepper, and garlic granules, and toss until each slice is evenly coated.
Arrange the slices on your prepared baking sheet, ensuring they don’t overlap. Overcrowding traps steam, resulting in soggy squash instead of crispy edges.
Roast for 20 minutes, then carefully flip each slice with tongs or a spatula. Continue roasting for another 20 minutes, or until the squash is soft and golden brown.
Before serving, garnish with fresh thyme, a sprinkle of flaked sea salt, and a pinch of crushed red pepper if you like. Serve warm and enjoy!