Special equipment: large bread bowl, 12 by 18-inch baking sheet or two smaller sheets
Place water in a large bowl. Water should be warm but not hot to the touch. Stir in the yeast and allow to dissolve. Stir in 1 cup flour, stirring constantly in the same direction. Stir in another cup flour, then stir 100 times in the same direction (one minute). This helps develop the gluten. You now have a sponge. Cover, and let stand for half an hour or up to three hours. When you are ready to continue, sprinkle on salt and oil, then add more flour, stirring it in a half cup at a time. The dough will be getting heavier and harder to stir. When you can stir no longer, flour a kneading surface well and have more flour handy beside your work surface. Turn dough out and knead, adding extra flour to your work surface as necessary to prevent the dough from sticking. The dough will gradually become smooth and easy to work. Knead for 10 minutes, clean bread bowl, oil it lightly, and place the ball of dough into the bowl to rise, covered with plastic wrap. Let rise until more than doubled, almost three hours. When the volume of the dough has approximately doubled, you can proceed to the next step.
Dough can be made ahead to this point and then stored. If you wish postpone baking, gently push dough down, and leave covered in the bowl to rise again. If delay will be more than several hours, instead store dough in a plastic bag in the refrigerator (for not more than five days). Bring out of the cold and take out of the plastic bag at least an hour before you want to work with it.Lightly flour your work surface and lightly oil a 12 by 18-inch baking sheet. Preheat oven to 450 degrees. Turn dough out onto work surface and flatten with the lightly floured palm of your hand. Pull and stretch the dough gently out into the rectangular shape you need to fit your baking sheet. Take your time and give the dough time to rest if it is resisting stretching. It will need to get quite thin. When you have stretched the dough to approximately the shape and size you need, transfer it to baking sheet and continue to gently press and stretch it to fit. Don't worry if it tears, just patch the hole with another piece of dough and press firmly to join the edges. If you have extra dough hanging over the edge, trim it off and use it to make another small pizza. Dough should be of an even thinness across the flat part of the baking sheet and should form a slight rounded rim as it meets the edge (which is for many people the best part of the pizza).
Brush top of pizza with oil, then dimple the surface all over with your fingers. Sprinkle garlic, sea salt and then optional rosemary leaves. Place baking sheet on the bottom rack of the preheated oven and bake until the crust around the edge is slightly golden, 5 to 8 minutes, depending on how thin the pizza is. Remove from oven, brush crusts lightly with olive oil and also the center if you wish. Cut into large squares and serve warm or hot. We have often made pizza bianca several hours ahead, then wrapped it in a clean kitchen towel to keep it moist until we are ready to reheat it for serving. To reheat, place in a dampened paper bag in a 300 degree F oven for about 10 minutes.