Begin by preheating the oven to 400 F/205 C.
In a small bowl whisk together the flour, sugar, and salt.
Add the eggs and vanilla extract to a large bowl and whisk them together. Then heat up the milk so it is lukewarm (about 100 F/37 C) and add that into the batter.
Dump all the flour mixture in and whisk. The popover batter should be runny.
Alternatively, put the eggs, vanilla, milk, flour, sugar, and salt in a blender and blend until all mixed.
Melt the butter and then baste each cavity of the muffin pan with the butter. Place the pan in the oven by itself for 2 to 3 minutes. Remove the pan with an oven mitt and then fill each cavity up with the batter equally using a 1/4th cup measuring spoon. They will be about 2/3rds full.
Bake in the oven for 23 to 25 minutes, until they puff up and are golden brown on top. Do not open the oven until at least 20 minutes have passed. Allow them to cool in the pan for just a few minutes before removing and place on a wire rack to cool further. Use a spoon to help pry them out if they are sticking. Serve with your favorite pancake or waffle toppings. Enjoy!