Combine warm water, yeast, and sugar in a large bowl; let sit for five minutes or till bubbly. Add olive oil, yogurt, egg, salt, and flour. Stir till smooth.
Start with 2½ cups and add more flour a few tablespoons at a time only as needed. The dough should be soft and slightly tacky, not stiff. Knead a few times on a floured counter until smooth. Place dough in a greased bowl.
Cover and let rise in a warm place until doubled in size, about 1 hour.
Preheat a skillet to medium heat. Cut dough into eight pieces. On a floured surface, roll out each piece into a 6-inch circle.
Heat a cast iron skillet over medium-high heat until very hot. The dough should begin bubbling shortly after it hits the pan. Add a little oil or non-stick spray to the skillet.
Cook about 1 to 2 minutes on the first side, until bubbly with deep golden spots, then flip and cook another 30 to 60 seconds. NOTE: The naan is ready to flip when large bubbles form on top and the underside has deep golden brown spots.
Keep it soft. Stack the cooked naan on a plate and cover with a clean kitchen towel while you cook the rest.
Brush the top (the bubbly side) of each naan with melted butter. Add 2 teaspoons garlic to 2 tablespoons butter (opptional).