In a medium sized pot, heat the milk, butter, and salt until it starts to boil. Remove the pot from the heat and using a wooden spoon vigorously mix the flour into the milk. Let the dough cool a bit and then using beaters on low speed, add one egg in at a time incorporating the eggs into the dough. You can also transfer the dough into a stand mixer and do this. Let the batter rest for at least 2 hours.