1. Dissolve yeast in warm water in a large bowl; let stand 5 minutes. Stir in yogurt. Add ½ cup bread flour and the 1 cup whole wheat flour to yeast mixture. Stir with a whisk until smooth. Cover and let rise in a warm place (85°F), free from drafts for 2 hours. Batter will be bubbly, lacy, and weblike.
2. Stir in salt and oil. Add 1½ cups bread flour ½ cup at a time; stir with a wooden spoon. Dough will become very difficult to stir.
3. Turn dough out onto a lightly floured surface. Knead until smooth and elastic (about 10 minutes); add enough of remaining bread flour 1 tbsp at a time to prevent dough from sticking to hands. Dough will feel tacky. Place dough in a large bowl coated with cooking spray, turning to coat top. Cover and let rise in a warm place (85°F), free from drafts, 2 hours or until doubled in size. Press 2 fingers into dough. If indentation remains,the dough has risen enough.
4. Place pizza stone on the bottom rack in oven. Preheat oven to 500°F.
5. Punch dough down; turn out onto a lightly floured surface. Cover and let rest for 5 minutes.
6. Divide dough into 8 equal portions. Working with one portion at a time, stretch each portion into a 6-inch oval. Keep remaining dough covered to keep from drying. Cover naan pieces and let rest 5 minutes.
7. Make indentations in top of dough portions using the handle of a wooden spoon or your fingertips; cover and let rise 20 minutes.
8. Place 2 dough portions on the back of a pizza peel dusted with cornmeal. Slide onto preheated pizza stone or baking sheet lined with parchment. Bake at 500°F for 6 minutes or until lightly browned. Repeat with remaining dough. Serve immediately.