Preheat oven to 400ºF.
Slice spaghetti squash in half lengthwise and scoop out seeds.
Drizzle halves with olive oil and place down on baking sheet and roast until tender, about 40-45 minutes.
Using a fork, shred squash into spaghetti-like strands. Let lightly cool in a mixing bowl.
Add egg and cheese.
Pour mixture into a greased baking pan. Bake for 30 minutes, or until edges are slightly golden.
Remove from oven, add sauce, cheese, and desired toppings.
Bake for another 10 minutes, or until cheese is fully melted.