Melt the butter in a large saucepan over medium-high.
Add the milk and salt to the butter and stir to combine, then allow the mixture to come to a boil (it should develop a frothy head).
Add the flour to the butter mixture and stir with a fork until a loose ball is formed. Continue stirring for 1 or 2 more minutes.
Scrape dough ball into a bowl and allow to sit at room temperature for about 5 minutes.
Add the eggs 1 at a time, stirring each into the mixture until it's smooth.
Preheat oven to 375 degrees F.
Coat 12 muffin cups with butter liberally, including the area around the mouth of each cup. Do the same to a #9 disher (one of those ice cream scoops with the thumb lever that helps push out the scoop). Drop about half a scoop of the mixture into each muffin cup. Dust the top of each puff with a pinch of sugar (turbinado sugar works well for this).
Slide pan into the oven and allow to bake for 30 minutes, until puffs have more than doubled in size and are golden brown.
Poke each puff with a fork to let out its steam (so the insides don't get soggy) and remove from the pan. Allow each puff to cool slightly before eating, then dig in!