Place 1 teaspoon of butter in each of the 6 cavities of a popover pan. Set aside.
In a large bowl, whisk together the flour and salt.
Stir in the browned butter.
Whisk in the milk.
Add the eggs, one at a time, beating well after each addition.
Continue beating until batter is smooth.
Place popover pan in oven for 4-5 minutes, until butter has melted and is starting to brown.
Remove pan from oven.
Pour batter into pan, filling each cup 3/4 full.
Bake for 15 minutes.
Reduce heat to 350 degrees F.
Continue to bake for an additional 20 minutes, until brown.
Notes
You could use a muffin tin instead of a popover pan. If you do, use 1/4 cup batter per standard-sized muffin. These popovers will also be smaller than what you would make in a popover pan.
It takes 1/2 cup of batter to fill each popover cup 3/4 full.