In a large measuring cup, whisk together the starter, milk, and Greek yogurt.
In a separate bowl, whisk together 1 cup of the flour, baking powder, and salt.
Pour liquid ingredients into dry and whisk until a loose, somewhat sticky dough is formed. If dough seems too sticky, add additional flour, 1 tablespoon at a time. Dough is ready when it is tacky but not sticky. Cover with a clean dish towel and let rest in a warm place for 1 – 2 hours.
Turn dough out onto a lightly floured surface and knead until smooth, about three minutes. Cut into four equal pieces.
Using a lightly floured rolling pin, roll out each piece of dough into a circular/oval shape. Cover again with a dishtowel and let rest for five to ten minutes.
While the naan rests, preheat a large griddle over medium-high heat. One by one, place the shaped naan onto heated surface. Cook for three to four minutes on one side, dough should puff up and form bubbles, kind of like pancakes. Flip over and cook for three to four minutes more. Repeat process with remaining dough.
While naan is still warm, brush with melted butter and sprinkle with additional salt, fresh garlic, chopped parsley or other seasonings, if desired.