Add flour to a large bowl.
In a separate mixing bowl, use a wire whisk beat eggs, whole milk, and salt together. Add egg mixture to flour, stirring until you have a smooth batter.
Finally, add in the melted butter and stir.
Let the batter rest for 15 minutes to an hour. I’ve found this step to be crucial to getting a good rise on my popovers. It doesn’t take long, 15 minutes really does do the trick, but you do need to let everything rest while the oven preheats.
Heat oven to 450 degrees F.
Set the popover pan (or muffin pan) in the preheated oven for 10 minutes.
Carefully take the hot pan out of the oven, setting it on oven mitts, and spray with cooking spray to grease.
Divide batter to fill each popover cup ¾ full. (I usually get 8-9 mini popovers.) Place berries over the tops of each popover, dividing blueberries equally.
Bake at 450 for 15 minutes.
Lower oven to 350 degrees, without opening the door, and bake for an additional 8-10 minutes.
When you take out of oven, pierce with a paring knife to let out steam and avoid collapse.
Dust tops of popovers with icing sugar and serve with butter and blueberry jam, lemon curd or honey.