Preheat the oven to 425°F.
Butter and flour your popover or cupcake pan. If you are using a cupcake pan, liners are an option.
Add the flour, salt, eggs, butter and milk to a food processor. Process until the ingredients are combined, scraping down the sides if necessary. Be careful not to overmix.
Add the dried thyme and cheeses and pulse until just combined.
Pour the batter into the cups, filling them about half way full.
Bake for 30 -35 minutes until golden brown.
Remove the popovers from the oven and allow to cool on a wire rack.
You can make these ahead and serve at room temperature but they are at their best when served warm from the oven!