05Now add the flour, salt, and 3 tablespoons of melted butter to the blender, and mix until thoroughly combined and frothy.06After five minutes have passed, remove the muffin tin from the oven and quickly grease each cup and the top of the tin with the additional melted butter.07Give the blender a quick pulse to ensure the batter hasn't settled and fill each cup about 2/3 full.08Bake for 30 minutes — NO PEEKING! This is very important. Do not open the oven door until 30 minutes have passed, or your popovers may collapse.09Remove from the oven and immediately turn out onto a clean towel or cooling rack. If the popovers are to be served later, prick the side of each with a fork to allow the steam to escape and prevent them from becoming mushy.10For the Cinnamon-Sugar Topping: Combine the cinnamon and sugar in a bowl and melt your butter in a separate bowl.11Brush each popover top with melted butter and dredge in the cinnamon-sugar mixture.