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Preheat oven to 400°F. and line pizza pan with parchment paper (or spray with cooking spray).
Place warm water, yeast and sugar into mixer bowl with the dough hook attachment on. Mix gently and let nearly double in size, about 5 minutes.
With mixer on low, add flour, olive oil, salt and garlic salt. Scrape sides of bowl and let knead for 5 minutes until dough is cleaning sides of bowl. Add sprinkles of additional flour if it's not.
Remove dough with floured hands and transfer to a floured countertop. Fold dough over itself a couple times then form into a round.
Place dough onto pizza pan and press into a 12-inch round (or larger for a more thin crust). Spoon sauce over dough leaving 1 inch around edges. Top with 1/2 cup of mozzarella, then layer with sausage, bell peppers, onions, zucchini, mushrooms and top with remaining mozzarella cheese.
Bake for about 15 minutes, until crust is cooked through. Remove and let cool for 5 minutes before slicing into wedges. Serve with a salad if desired.