In a large mixing bowl, add the eggs and the milk and beat gently. Once combined, add the flour a little at a time and whisk in intervals until well combined. Add the melted butter and salt and whisk gently.
Let the batter rest for one hour or up to a day in the fridge.
To cook the crepes, melt a teaspoon of butter in a non-stick pan (or a seasoned cast iron pan) on medium heat. Pour in a ladle of batter and swirl it around so that the batter evenly coats the base of the pan. Let the crepe cook until the edges just begin to turn a golden brown. I like to check the doneness of the crepe by lifting it gently with a silicone spatula. If it self-releases (which takes around 1 minute), it is ready to be flipped. Let it cook on the other side for just under a minute and turn over the crepe on a plate.
Add more butter to the pan and continue to cook the rest of the crepes.
To make the lemon curd:
Whisk the eggs and yolks together in saucepan or pot. Place the pan on the stove and bring to a low heat. Add the sugar, lemon juice and zest.
Using a whisk, gently whisk the ingredients until the sugar is almost dissolved.
Add the butter and continue to whisk, on low heat until the mixture thickens. This should take around 7-10 minutes. Once the lemon curd has thickened, turn off the heat and take the pan off the stove.
Strain the curd through a sieve and transfer to a glass jar. You can keep it refrigerated for upto 2 weeks.