3tbspplain full-fat yogurt(if you only have Greek yogurt, thin it out with a little milk or water to the consistency of regular yogurt)
In large measuring cup, combine water, yogurt, and olive oil. Set aside.
In bowl of stand mixer, whisk together flour blend, baking powder, yeast, sugar, and salt. With mixer running on low speed, using paddle attachment, slowly pour in wet ingredients until incorporated. Mix on medium high for about 5 minutes. Alternatively, the dough can be mixed vigorously by hand in a large bowl with a dough mixer or wooden spoon (you're sure to get an arm workout).
Cover bowl with plastic wrap and allow to rise at room temperature for about 2-4 hours (depending on how warm your kitchen is), until doubled in volume.
Refrigerate dough for a couple of hours until well chilled. This can be done overnight, or even up to 3 days ahead.
Remove dough from refrigerator and knead briefly on well-floured surface. Dough is very sticky, so use as much extra bread flour blend as necessary to prevent sticking. (You may also use tapioca or cornstarch). Divide into 6 equal pieces and roll each piece into an oblong flatbread about 1/8 to 1/4 inch thick, using more flour as needed.
Heat cast iron skillet to scorching hot (you will need adequate ventilation for this--outside on a grill is another option).
Using bench scraper, lift one flatbread off surface and carefully flip over onto skillet. "Bake" for 1 minute. Flip over using spatula and cover skillet and "bake" for another minute. Remove from skillet, place on baking sheet and brush with butter. Bake the rest of the naan, one at a time. Serve warm wrapped in towel.
Store wrapped in foil on counter for just a few days. To reheat, preheat oven to 350° and reheat naans wrapped in foil for about 15 minutes, or until heated throughout. May be frozen well wrapped for 3 months.