Preheat your oven to 400 degrees Fahrenheit. Line a half-sheet pan with parchment paper or foil lightly coated with nonstick spray, and set aside.

Using a sharp chef's knife, carefully pierce the spaghetti squash 4 to 5 times around its center. Microwave the squash for 2 minutes, flipping it halfway through. Let it cool for 5 minutes before handling.

Place a damp paper towel under a large cutting board to keep it steady. Set the squash on the board and slice off both ends, discarding them.

Cut the squash into 1.5-inch thick rings. Rock the knife while rotating the squash to make clean cuts instead of sawing. Use a spoon or knife to scoop out the seeds from each ring, then arrange the rings on the prepared baking sheet.

Drizzle the rings with olive oil and sprinkle with salt, pepper, and garlic powder. Rub the seasoning over both sides of each ring, including the inner edges. Roast for 25 to 35 minutes, flipping the rings and rotating the pan halfway through, until the squash shreds easily with a fork.

Shred the roasted squash with a fork and use immediately, or let it cool to room temperature and store in a covered container in the fridge for up to 5 days. Reheat in the microwave before serving.