Preheat oven to 400°F. Carefully cut your spaghetti squash in half with a large, sharp knife. Remove seeds and stringy guts, and brush the cut sides of the squash with 1 tablespoon of olive oil. Season with Kosher salt and freshly ground black pepper. Place spaghetti squash, cut side down, on an aluminum-lined baking sheet and roast until tender, about 45-60 minutes.
To test if your squash is done, scrap the flesh with a fork. If the strands come off easily, it's done. Let the cooked spaghetti squash cool for about 5 minutes, then scrape all the flesh into a beautiful pile of spaghetti strands. Taste and season with some more Kosher salt and freshly ground black pepper if needed.
Measure out approximately 3 and ½ cups of spaghetti squash. Reserve rest for another use.
Wrap measured-out squash in a cheesecloth, clean kitchen towel, or several layers of paper towels*. Squeeze out as much moisture as possible. The drier the squash, the more crispy the crust can get.
In a medium mixing bowl, combine the squash, egg, mozzarella cheese, parmesan cheese, and season with Kosher salt and freshly ground black pepper. Press squash in a thin, even layer on a parchment-lined baking sheet and form into an approximate 10-inch circle.
Bake at 400°F for approximately 20 minutes. Remove from oven, carefully flip, and cook for another 10 minutes.
Add desired toppings and bake until done.
*Dawn simply pats the squash mixture (once pressed out in the jelly roll pan) with paper towels to absorb the extra moisture.