Move a rack to the lower third position of your oven. Preheat to 450° F or 232° C. With cooking spray, give your muffin tin a generous spraying.
In a large measuring cup, bowl with spout, or medium sized bowl, add the eggs and milk, whisking to lightly combine. Add the remaining ingredients up to the bleu cheese and whisk more vigorously but don’t over mix. There should be a few lumps remaining.
Divide the batter evenly between the muffin wells, leaving about 1/4” of space to the rim, and drop just shy a teaspoon of blue cheese to the tops of each (maybe a bit more if you’re making larger popovers).
If using a regular size muffin tin: bake for 15 minutes without opening the oven. Lower the temperature to 350° F or 176° C and continue to bake for about 12-15 minutes or until the popovers are nicely golden and puffy.
If using a mini muffin tin: bake for 10 minutes without opening the oven. Lower the temperature to 350° F or 176° C and bake for an additional 8-10 minutes, until the popovers are nicely golden and puffy.
Remove the popovers from the tin straight out of the oven and serve immediately. You may also let these cool completely then reheat in the oven for about 10 minutes at 350° F/176° C.