In a small bowl, stir together the warm water, yeast, and sugar. Let stand at room temperature, until foamy, about 5 to 10 minutes.
In the bowl of a stand mixer fitted with a dough hook, stir together flour and salt. Add the yeast mixture, yogurt, and oil. Mix on low speed until just combined, scraping down sides of bowl as needed. Increase mixer speed to medium. Knead until dough becomes smooth, about 8 to 10 minutes. Place in a large greased bowl, cover, let rise in a warm, draft-free place, until doubled in size, about 1 hour.
Punch down the risen dough. Divide into 8 equal pieces and shape into balls. On a lightly floured surface, roll each into roughly 8-inch long ovals. (If you’re limited on counter space, stack rolled dough on a baking sheet lined with parchment or wax paper with a piece of paper between each dough piece.)
Heat a 12-inch cast-iron skillet over medium heat. Working with one piece at a time, spray the skillet with cooking spray and add a rolled dough to the hot skillet. Cook, until the dough starts to puff and is golden brown on the bottom, about 1 to 2 minutes. Flip and cook until golden brown, another 1 to 2 minutes. Remove from the skillet and cover with a tea towel to keep warm. Repeat with remaining dough, coating the pan with cooking spray before adding the dough each time.
In a small bowl, stir together melted butter and garlic, if using. Brush both sides of each naan with garlic butter. Serve warm.