Sift the flour into a bowl and add the salt. Make a small well in the centre, add the eggs and whisk. Add half the milk and gradually whisk in more flour from the sides. Add the rest of the milk and whisk until the batter is smooth. Let it rest for about 30 minutes so the flour absorbs the milk. Check the batter: it should be as thick as pouring cream, so whisk in a little more milk if needed. Heat a pan over medium heat, add a little butter and spread it over the pan with a paper towel. Ladle in some batter and swirl the pan so it spreads thinly to the edges. Flip once the edges start to lift. Butter the pan again before each pancake. Serve warm with maple syrup.