Whisk together the eggs, salt, cayenne pepper, milk, oil, and Bisquick mix in a large measuring cup or mixing bowl until smooth.
Wrap the bowl in plastic wrap and set it aside for 1 hour in a cool place, such as the refrigerator.
Grease 14 nonstick muffin cups using butter and then mist them with cooking spray.
Whisk together the batter for a few seconds, then fill each prepared muffin cup four-fifths full. Sprinkle half of the blue cheese evenly over each muffin.
To make popovers, preheat the oven to 450 degrees F (230 degrees C). Place muffin pans in a cold oven with a drip pan set underneath. Set the temperature to 450 degrees F (230 degrees C).
Bake them until popovers are well browned and fully puffed, about 30 to 35 minutes.
Finally, get them out of the oven and serve straight away.