Step 1Heat the oven to 450 degrees. Spray the cups of two popover pans with nonstick cooking spray, then drizzle 1 tablespoon melted butter evenly among the 12 cups; set aside.
Step 2In a medium bowl, whisk together the milk, eggs, zest and remaining 3 tablespoons butter until combined.
Step 3In a large bowl, whisk together the flour and salt. Add the egg mixture to the flour mixture and whisk thoroughly until smooth, 1 to 2 minutes.
Step 4Divide the batter among the cups in popover pans, then sprinkle the cheese evenly over the batter.
Step 5Put the pans in the center of the oven and bake, without opening the oven, for 20 minutes. Reduce the temperature to 325 degrees and continue to bake until dark golden brown and crisp, about 15 minutes more.
Step 6Remove the popovers from the oven and immediately poke each with a thin metal skewer, cake tester or the tip of a paring knife to allow steam to escape. Turn the popovers out of the pan and dust with powdered sugar, if you like. Serve immediately, or reheat later in a 350-degree oven until just crisp.