First, melt 28 g (1 oz) (2 tbsp) of butter and set aside to cool.
Sift the flour and salt into a large mixing bowl and make a well in the centre.
Beat the eggs in a bowl, then add the milk and cooled, melted butter. Gradually pour the mixture into the well of the flour while whisking with an electric whisk or a balloon whisk, incorporating the flour from around the edge of the bowl. Scrape any remaining flour down from around the sides of the bowl using a silicon spatula and whisk again until all the mixture is smooth. Let stand for 20 minutes.
Meanwhile preheat oven to 110°C/225°F/gas ¼, and place five plates in the oven to warm.
Melt the remaining butter and pour into a small bowl.
Get the pan really hot, then turn the heat down to a medium setting.
Smear the pan, using kitchen paper, with a little melted butter to keep it lightly greased. (The pan should be lightly coated, not running with butter.) Repeat before cooking each pancake.
Use about 3 tablespoons of batter for each pancake. (It is easier to measure this into a ladle or cup first to give a guide for the amount for each pancake.) Quickly tip the batter from the ladle or cup into the centre of the pan and, at the same time, tip the pan from side to side to get the base evenly coated. Cook the pancake for about 1 minute until the surface dries and the underside is golden.
Flip the pancake over with a palette knife. Again, cook until the underside is golden which will need less time. Then slide out of the pan onto a warmed plate.
Continue until the batter is finished. Overlap the pancakes on the warmed plate as you go. Keep them warm in the oven, covered loosely with foil.
To serve, squeeze lemon juice over each pancake and generously sprinkle with sugar. It can then can be rolled up.