Adjust oven rack to lower-middle position and heat oven to 450 degrees.
Grease interior of 6-cup popover pan with shortening, then dust lightly with flour.
Whisk eggs until light and foamy in medium bowl. Slowly whisk in milk and butter until incorporated.
Combine flour, salt and sugar in large bowl. Whisk 3/4 of milk mixture into flour mixture until no lumps remain, then whisk in remaining milk mixture.
Transfer batter to large measuring cup, cover with plastic, and let rest at room temp for 1 hour. (Alternately, batter can be refrigerated for 1 day. Bring to room temp before proceeding).
Whisk batter to recombine, then pour into prepared popover pan (batter should not reach the top of cups).
Bake until just beginning to brown (about 20 minutes). Without opening oven, decrease temp to 300 degrees and continue to bake until popovers are golden brown all over (35-40 minutes longer).
Poke small hole in top of each popover with skewer and continue to bake until deep golden brown, about 10 minutes longer.
Transfer popover pan to wire rack. Poke again with skewer and let cool 2 minutes.
Turn out popovers and serve!
Make ahead: Once cooled, popovers can be stored at room temp in ziplock bag for 2 days. To serve, adjust oven rack to middle position and heat to 400 degrees. Heat popovers on rimmed baking sheet until crisp and heated through (5-8 minutes).
If making in a muffin pan instead: Fill 10 outer cups to 1/4 inch from the top). Reduce initial baking time to 15 min and 2nd baking time to 20-25 minutes after oven temp has been lowered. Disregard final baking time of 10 minutes. Poke as directed when removed.
Instructions - Honey Butter:
Mix butter, powdered sugar, honey and cinnamon until well combined and creamy.
Nutrition Info Per Serving (1 Popover with no butter): Calories 304.5 Total Fat 11.6 g Saturated Fat 6.2 g Polyunsaturated Fat 1.0 g Monounsaturated Fat 2.5 g Cholesterol 120.2 mg Sodium 504.9 mg Potassium 215.3 mg Total Carbohydrate 38.0 g Dietary Fiber 1.1 g Sugars 4.6 g Protein 11.3 g