I love roasted butternut pumpkin, but not roasted regular pumpkin. The result is completely different. This is what butternut pumpkins look like:
Generally being good at roasting food helps you to pull this recipe off to perfection.
Cut the pieces of pumpkin to small pieces, use your judgement for size. Add salt (use judgement), ghee (preferred to vegetable oil or olive oil), some garlic cloves, and sprinkle with rosemary and nutmeg:
After 45 minutes of baking at 160 degrees C:
The image above looks a little too light. You could go a little longer for more browning and crisp, and how big you cut your pieces.
I suggest checking at 45 minutes of baking, take it out, taste some, then put it back in the oven for another 10 minutes, and taste and compare. Learn what you like.