Split squash in half lengthwise and remove seeds and membranes with a spoon. Brush the flesh of each squash with 1/2 teaspoon olive oil, then sprinkle with 1/4 teaspoon salt and a pinch of pepper.
Place squash, skin side up, in a 9x13" glass baking dish. Microwave on full power for 15-20 minutes. Let sit about 10 minutes and then use a fork to shred squash into a large serving bowl.
While squash is cooking, heat 1 teaspoon oil in a large nonstick skillet over medium heat. Cook onion and garlic until onion is beginning to soften, about 3-5 minutes.