Preheat oven to 450. Place the popover pan into the oven for 10 minutes to preheat.
Pour the milk into a medium saucepan, and warm gently over medium-low heat until it’s lightly steaming, and approximately 120 degrees. Remove from heat.
Crack the eggs into a bowl (to double check there are no shells in the popovers), and pour them into a large blender. Process until frothy, and no streaks of yellow remain.
Add the melted butter, flour, cheese, dill, salt and pepper to the blender. Process until smooth. Remove the popover pan from the oven, and spray liberally with cooking spray. (Inside the cups, and around them on top of the pan.)
Pour mixture halfway up the cups.
Bake for 20 minutes.
Without opening the oven door, turn the heat down to 350 degrees.
Bake for an additional 10 minutes or until golden brown and crispy.
Remove the pan from the oven, and cut a slit in each popover. Run an offset spatula around the popovers to release them, and place them on a cooling rack.
Preheat the oven back up to 450 degrees.
Let the pan cool for a few minutes and wash and dry if needed.
Pour remaining popover batter halfway up the cups, and repeat the process.
Serve warm or at room temperature. Store in a paper bag in the refrigerator for up to 3 days.