Position a rack in the lower third of the oven. Preheat the oven to 450°. Place 1 teaspoon of butter in a 6-cup standard popover pan. Alternatively, you can use a 12-cup muffin pan and make 10 mini popovers. Transfer the popover pan to the oven. After 5 minutes, remove the pan from the oven.In a blender, combine the milk and eggs, blend for 30 seconds, until frothy. Add the flour, salt, and melted butter. Blend another 30 to 60 seconds until combined with no large clumps. Evenly divide the batter between the popover cups, filling them about 3/4 of the way full. Transfer to the oven and bake for 20 minutes. Lower the oven temperature to 350°. Bake another 15-20 minutes, until puffed, golden and crisp. Serve immediately with salted butter, honey butter, or cranberry butter. Cranberry Butter: Mix together 6 tablespoons of room-temperature salted butter and 1/3 cup leftover cranberry sauce or cranberry jam. Add 1-2 tablespoons of honey and a pinch of sea salt.Salted Honey Butter: Mix together 6 tablespoons of room-temperature salted butter, 3 tablespoons of honey, and a pinch of sea salt. If desired, add 1/2 teaspoon vanilla extract. Serve popovers with extra honey too!