Preheat oven to 425 degrees.
In a large bowl, mix dry ingredients. Stir in water and olive oil, forming a soft dough—adjust water as needed. Knead a minute or so on a lightly floured counter. Close up dough into an airtight tub and set aside to ferment for 45 minutes.
While dough is resting, prepare the butternut. Peel squash and cut in half. Remove inner seeds. Cut squash into small cubes. Put in a bowl, toss with avocado oil, salt, and pepper. Roast in oven for 25 to 30 minutes, until squash begins to brown.
While squash is cooking, grate cheeses. When squash is finished, turn oven temperature up to 500 degrees.
Once dough has risen, punch down and roll out onto a pizza stone or baking pan (I like to use a rectangle). Top with cheeses and roasted squash. Bake for about 20 minutes, until crust become golden brown.
While pizza is cooking, heat balsamic vinegar over medium heat. Cook for 15 minutes, stirring frequently, until reduced to about half. Remove from heat (sauce will continue to thicken).
When pizza comes out of oven, immediately top with arugula. Drizzle balsamic reduction over the top and serve.