Preheat oven to 350F and lightly grease an 8-inch round baking pan with cooking spray.
Roll out challah dough into a thin rectangular shape about 24 inches long by 10 to 12 inches wide.
Mix chopped cilantro with chopped scallions and oil together in a bowl, add red chili flakes if using. Brush mixture over the surface of the dough. Working from the longer side gently roll up the dough like a jelly roll and slice into 8 equal pieces.
Arrange 7 pieces around the circumference of the pan with the 8th in the middle so they are tightly packed.
Bake at 350F for 40 to 45 minutes. Remove from oven and allow to cool in the pan for about 10 minutes.
