Mix wet ingredients. Combine the sourdough discard, milk, yogurt, and oil in a large mixing bowl.
Add dry ingredients. Next, add the flour and salt.
Mix. Using a wooden spoon or spatula, mix all of the ingredients together so they are well combined. If you are having trouble incorporating the rest of the flour, turn the dough onto a clean, dry surface and knead the rest in.
Prepare for rising. Turn the dough onto a clean, dry surface if you haven’t already done so. Lightly spray a bowl with baking spray, and place the dough in the lightly greased bowl.
Rise. Cover the bowl with plastic wrap and let it sit at room temperature until it doubles in size, about 8-12 hours (or overnight).
Divide and rest. Once your dough has doubled in size, turn it out onto a clean, dry surface and divide it into 8 equal portions. Let the dough rest for 30 minutes.
Roll out. Dust your surface with a small amount of flour (to prevent the dough from sticking), and using a rolling pin, roll out the dough so it is about a ¼ inch thick. Transfer to a lightly floured surface or a parchment-lined baking sheet and set aside.
Cook. Heat a cast iron skillet over medium heat and allow it to come to temperature. Place a rolled-out dough naan in the warmed skillet and cook for about 3-5 minutes on each side or until bubbles start to form and the dough is browning.
Garnish (optional). Brush the top of the naan with olive oil or melted butter. Sprinkle it with some flaky salt and parsley.