Deep Dish Pizza (Veggie Version)

See also Meaty Deep-Dish Pizza. I often make one of each.
Ingredients
Crust

• 1 C water
• 1/4 C olive or vegetable oil
• 1 1/2 Tbsp sugar
• 2 1/4 tsp salt
• 3 1/2 tsp active dry yeast
• 1/2 C lukewarm water
• 3/4 C cornmeal
• 2 C all-purpose flour
• 1 1/2 C whole wheat flour

Sauce

• 2 28-oz cans Italian style diced tomatoes, drained
• 1 large onion, chopped
• 1 small green bell pepper, chopped
• 1 small red bell pepper, chopped
• 1 1/2 tsp oregano
• 1 tsp fennel seed
• 1 tsp salt
• 1/2 tsp black pepper ground
• 4 Tbsp olive oil

Filling

• 4 Tbsp olive oil
• 2 medium onions, cut into thin strips
• 4 cloves garlic, minced
• 2 C sliced portabella mushrooms
• 1 1/2 tsp basil
• salt & pepper to taste
• 2 boxes chopped spinach
• 4 C mozzarella cheese, shredded
• 1 C Feta cheese, crumbled
• 1 C Parmesan cheese, shredded

Instructions
For crust:
In work bowl of a stand mixer fitted with dough hook, combine dry ingredients. With mixer running on medium-slow speed, drizzle oil in a slow stream and mix until combined. Add water in a slow stream, only as fast as flour can absorb, until dough forms and begins to clean the sides of the bowl. Increase speed and knead for several minutes until smooth and elastic. Dough may be quite soft, but if it is too sticky knead in a bit more all-purpose flour. If it is too stiff, and more water, a small splash at a time. Remove the dough hook and gather the dough into a ball. Allow to rest about 5 minutes. Meanwhile, preheat oven to 425° and prepare 2 12-inch round deep-dish pizza pans. If using stoneware bakers, no preparation is needed. If using metal pans, brush with oil. When dough has rested, divide in half and press evenly over bottoms and up sides of the pans. Prick all over with a fork. Bake in preheated 425° oven for 5 minutes
For sauce:
In large skillet, saute onion, peppers, herbs, and spices in olive oil until peppers and onion are tender. Stir in well-drained tomatoes & mushrooms. Cook lightly, then remove from heat.
For filling:
In a large skillet, heat the olive oil. Saute the onion and garlic until clear. Add the mushrooms, salt, pepper, and basil and continue to saute, until the mushrooms are softened. Meanwhile, thaw the spinach in a colander under running water, then squeeze out the excess water with your hands. Squeeze again, one handful at a time, until the spinach is as dry as you can make it. Add the squeezed spinach to the skillet and stir, breaking up the clumps to thoroughly combine all ingredients. When the spinach mixture is hot through and fragrant, remove from heat.
To assemble:
For each pizza, sprinkle just a scant handful of mozzerella in the bottom of the pre-baked crust. Next, spread half the spinach mixture evenly into the pizza crust. Sprinkle the spinach layer evenly with half the feta, then cover with a layer of half the remaining mozzarella. Spread with a layer of half the sauce. Top with half the Parmesan. Use the second half of the ingredients to assemble the second pizza. Bake the pizzas 20-30 minutes in at 425° oven, or until bubbly and golden-brown.