Heat oven to 400F with the popover pan or muffin tin in the oven to preheat as well.
In a large mixing bowl, combine the following ingredients in the order given: eggs, milk, flour, salt, butter, cheese, and thyme. Take care not to overmix, especially after adding the flour. The batter should stay a bit lumpy.
Remove the preheated pan from the oven and spray with cooking spray. Dust the insides of the tins with flour, shaking out the excess (this will give the dough something to cling to to help the popovers puff properly). Add the prepared batter to the popover or muffin tins filling each half full.
Bake at 400F for 30 minutes until puffed and golden. Pierce the tops with a knife and bake another 4 minutes. Remove from the oven and serve immediately. With butter. Yield: 6 popovers.