1 batch Push-Button Pizza Dough (August '00, p. 42)
1 Tbs. olive oil, plus more as needed
2 to 3 cups halved, thinly sliced onions
8 oz. baby spinach leaves, rinsed well (4 to 5 packed cups)
2 medium cloves garlic, minced
Prepare pizza dough as directed. (August '00, p. 42)
While dough is rising, in large, nonstick skillet, heat 1 tablespoon oil over medium heat. Add onions and cook, stirring often, until golden, about 8 minutes. Stir in spinach, sprinkle lightly with salt, cover and cook just until spinach wilts, about 2 minutes. Stir in garlic and vinegar, cover and cook 1 minute. Remove from heat and set aside.
Prepare grill, leaving one side unlit. Lightly oil 2 baking sheets. Gently punch down dough, divide in half and knead each half into a ball. Place dough balls on lightly floured surface, cover with plastic wrap and let rest 8 minutes. Using rolling pin, roll each ball into 9-inch circle, about 1/4 inch (scant) thick. Transfer to prepared baking sheets and lightly brush entire
surface with oil. Cover with plastic wrap and let rest 10 minutes.
Carefully lift each dough circle off baking sheet and place on hot side of grill. Cook undisturbed 1 1/2 to 2 minutes, so bottom has a chance to set; top of dough will bubble.
Using large spatula, flip dough over onto same hot side of grill and cook 1 to 2 minutes. Slide crusts to cooler area of grill. Evenly spread spinach mixture over crusts; season with freshly ground pepper to taste. Sprinkle with walnuts and provolone. Close grill and cook, periodically moving pizzas around to keep charring to a minimum, 3 to 4 minutes. Transfer pizzas to cutting board, dust with Parmesan if desired, slice and serve.