Whisk eggs and salt together in a bowl until light and frothy. Whisk in milk and flour until smooth and lump-free; batter will be thin and barely coat the back of a spoon.

Transfer batter to a 4-cup measuring cup. Chill in the refrigerator at least 15 minutes.

Preheat the oven to 400 degrees F (200 degrees C) with oven rack in center position.

Spoon 1 tablespoon melted beef fat into cups of a 12-cup nonstick muffin tin; use your finger to grease sides and tops of cups. Place the prepared tin on a baking sheet.

Place in the preheated oven until fat is smoking hot, 10 to 15 minutes.

Remove from the oven; spoon batter into the cups, filling each 1/2 full.

Bake in the preheated oven until browned and fully puffed, about 25 minutes. Remove from the oven; immediately poke a hole in center of each to release steam. Serve hot, warm, or room-temperature.