Filling Rinse spinach, shake off excess water. Transfer to pot. Cover and cook over low heat, stirring frequently, until just wilted, about 3 minutes. Rinse with cold water and squeeze dry. Chop coarsely.
Heat oil in heavy large skillet over low heat. Add onion and garlic and cook until soft, about 10 minutes. Mix in olives and raisins and cook two minutes, stirring frequently. Add spinach, red pepper flakes and pepper. Stir 5 minutes. (Can be prepared 1 day ahead. Cover and refrigerate. Bring to room temperature before continuing.)
Crust Sprinkle yeast over 1/2 cup warm water in small bowl. Stir to dissolve. Arrange 1 1/2 cups flour in mound on work surface and make a well in the center. Add yeast to well. Using fork, gradually draw flour from inner edge of well into center until all flour is incorporated. Knead sponge until smooth and elastic, 8 to 10 minutes. (Can also be prepared in processor. Knead 1 minute.) Lightly flour large bowl and add sponge. Cover with towel. Let sponge rise in draft free area until doubled, about two hours.
Arrange remaining 3 cups flour in mound on work surface and make well in center. Add raised sponge to well and pull to form well in sponge. Add remaining 1 cup water, 3 tablespoons oil and salt to well in sponge. Knead mixtures together until smooth and elastic dough forms, 8 to 10 minutes. (Can also be prepared in processor. Knead one minute.) Return to floured bowl. Cover with towel. Let dough rise in draft free area until doubled in volume, about 1 1/2 hours.
Mix cheese with 1 tablespoon oil. Add salt and pepper to taste.
Preheat oven to 400 F. Spread 3 tablespoons oil in bottom of 9 by 13 inch metal baking pan. Punch dough down. Cut into 2 pieces, one 1 1/2 times larger than the other. Roll large piece out on lightly floured surface into 11 by 15 inch rectangle. Fit dough into prepared pan, covering bottom and sides. Brush with remaining 2 tablespoons oil. Spread filling in pan and sprinkle with cheese. Roll remaining dough out on lightly floured surface into 9 by 13 inch rectangle. Brush edges with water and place atop filling. Pinch top and bottom crusts together. Brush top of pie with water. Cut three 3 inch slits in top. Bake until well browned, about 35 minutes. Cool slightly. Serve pie warm or at room temperature.