Preheat oven to 450 degrees Fahrenheit
Grease the bottom and sides of the popover cups with bacon grease. You can also use butter/vegetable oil if you want to make these vegetarian
Mix the flour, salt, and spices in a bowl and set aside
In the bowl of a stand mixer, combine the eggs and milk and whisk until well combined.
Add the flour mixture all at once and whisk on high speed for around 30 seconds. Scrape the sides of the bowl down with a spatula and whisk again on high speed for another 30 seconds.
Add the grated parmesan and melted butter to the mixture and stir to combine with a spatula.
Pour the batter into the greased popover tin. Fill the popover cups to no more than ¾ full. Grate more parmesan on top of the batter
Place in the oven and bake at 450 degrees Fahrenheit for 20 minutes.
After 20 minutes, without opening the oven door, reduce the temperature to 350 degrees Fahrenheit. Bake for another 10-15 minutes.
If serving the popovers immediately, poke with a knife to allow steam to escape, remove from the pan and serve.
If not serving immediately, bake a few extra minutes to help popovers hold their shape.