Preheat oven to 400 degrees F. Lightly oil a baking sheet or coat with nonstick spray.
Place butternut squash in a single layer onto the prepared baking sheet. Add olive oil, maple syrup, brown sugar, cinnamon and nutmeg. Gently toss to combine.
Place into oven and bake for 25-30 minutes, turning once, until tender.* Add pecans during the last 10 minutes of cooking time.
Serve immediately, garnished with rosemary, if desired.
Notes
Use a good quality sheet pan. A durable sheet pan is ideal – it will last for years with minimal wear and tear, and will help achieve even cooking and avoid warping at high temperatures.
Prep ahead of time. Save time by cutting the butternut squash 1-2 days prior and storing in an airtight container in the fridge.
Soften the butternut squash first. If the squash is too hard to cut through, pierce the squash a few times using a fork and microwave for 3 minutes. Let the squash cool for 10 minutes, or until it is cool enough to handle.
Make a stable base. Trim off the top and bottom to create a flat stable base for cutting.
Cut into uniform pieces. Dice the butternut squash into similar-sized 1-inch chunks to ensure even cooking throughout.
Avoid an overcrowded sheet pan. Spread the butternut squash in a single layer, allowing some space between the pieces. A crowded sheet pan will inevitably trap steam, yielding soggy butternut squash instead.
Roast at high heat. Roasting at 400°F will caramelize the natural sugars of the butternut squash, boosting the natural sweetness of the squash and yield crispy edges while keeping the inside tender and soft.