GORGONZOLA AND GRAPE PIZZA
1 (1/4-oz) package active dry yeast (2 1/4 teaspoons)
1 3/4 cups unbleached all-purpose flour
3/4 cup warm water (105-115°F)
1 teaspoon salt
1/2 tablespoon olive oil
1/3 cup Vin Santo
1 tablespoon sugar
1 1/2 cups red seedless grapes (9 oz), halved lengthwise
5 oz Italian Fontina, rind discarded and cheese cut into 1/4-inch dice (1 cup)
2 oz Gorgonzola dolce, crumbled
1/2 teaspoon coarsely ground black pepper
Special equipment: a pizza stone; parchment paper
Stir together yeast, 1 tablespoon flour, and 1/4 cup warm water in a cup and let stand until mixture appears creamy on surface, about 5 minutes. (If mixture doesn't appear creamy, discard and start over with new yeast.)
Whisk salt into 1 1/4 cups flour in a large bowl, then add yeast mixture, oil, and remaining 1/2 cup warm water and stir until smooth. Stir in enough flour (1/4 to 1/2 cup) for dough to begin to pull away from side of bowl. (This pizza dough will be slightly wetter than others you may have made.)
Knead dough on a floured work surface with floured hands, reflouring when dough becomes too sticky, but using as little flour as possible, until dough is smooth, soft, and elastic, about 8 minutes. Form dough into a ball and dust generously with flour. Put dough in a medium bowl and cover bowl with plastic wrap, then let dough rise in a warm, draft-free place until doubled in bulk, about 1 1/4 hours.
Shape dough and make topping:
At least 45 minutes before baking pizza, put pizza stone on oven rack in lower third of oven and preheat to 500°F.
Do not punch down dough. Gently dredge dough in a bowl of flour to coat, then transfer to a parchment-lined pizza peel or baking sheet (without sides). Lightly flour parchment (around dough). Pat out dough evenly with your fingers and stretch into a 13-inch round. (Do not handle dough more than necessary. If dough is sticky, dust it lightly with flour.)
Bring Vin Santo with sugar to a boil in a small heavy saucepan over moderate heat, stirring until sugar is dissolved, then boil, uncovered, until reduced to about 1 tablespoon, about 5 minutes. Add grapes to saucepan and stir gently to coat with syrup, then transfer to a bowl. Add cheeses and pepper to bowl, then stir to combine.
Arrange topping on dough leaving a 1-inch border.
Slide pizza on parchment onto pizza stone. Bake pizza until dough is crisp and browned and cheese is golden and bubbling in spots, 14 to 16 minutes. Using peel or baking sheet, transfer pizza to a cutting board. Cool 5 minutes and remove parchment before slicing.
Cooks' note: Dough can rise slowly, covered and chilled, 1 day ahead. Bring to room temperature before shaping.