Beat egg(s) with a wire whisk until light and fluffy
Whisk in milk
Whisk in flour and salt until no lumps remain.
Let the batter sit for at least 30 minutes (don't refrigerate)
Preheat oven to 450 degrees F
Place appropriate amount of whatever fat you're using in an appropriate-sized skillet or pan (see NOTES)
Place pan with fat in preheated oven. Let the pan/fat heat for about 5-7 minutes or until the fat is very hot and almost at the smoke point (you'll have to keep an eye on this, but I find it's ready in 5 minutes with drippings or duck fat)
Pour the batter into the hot pan and bake for 10-15 minutes or until the sides have puffed and are a nice golden brown.
The center will fall almost immediately after being removed from the oven--this is normal!
I HIGHLY recommend using cast iron skillets For a 2-egg batter, use a 8 or 9-inch skillet. It's better to use the smaller. For a 3-egg batter, use a 10-inch skillet For a 4-egg batter, use a 12-inch skillet.