Lofty, crispy-custardy, and just-barely sweet, these popovers work just as well as a last-minute dessert as they do an anytime treat. For Mexican chocolate popovers that would be very delicious served with a scoop of ice cream, add a teaspoon of ground cinnamon and a big pinch of chili powder to the dry ingredients. For plain popovers, swap the cocoa powder for all-purpose flour and omit the sugar. —Caroline Lange
unsalted butter, melted and separated
Whisk together dry ingredients in one bowl and wet ingredients in another, reserving 1 tablespoon of the melted butter. Pour the wet ingredients into the dry and whisk to combine thoroughly. Try to get any lumps out! Set the batter aside and let it come to room temperature while you preheat the oven to 425° F.
Grease the cups of a popover pan or muffin tin with the reserved butter, and when the batter is almost at room-temp, set the greased pan on a baking sheet and place in the oven to heat up for 5 or so minutes. You will hear the butter sizzling in the pan!
Carefully fill up the cups of the hot pan 2/3 of the way, then bake for 20 minutes. Reduce the heat to 375° F and bake 10 to 15 minutes more, until the popovers are well puffed and very fragrant. Trust your nose; it may be hard to tell visually if they are burning because of the chocolate. Do not open the oven at all during the baking (or else you risk collapse!).
Remove the pan from the oven and use a small, thin knife to pull the hot popovers out. Prick the bases of the popovers with the knife to help steam escape. Serve warm.