In a saucepan, warm the milk until steaming, and then remove from heat and set aside to allow it to cool slightly.
In a large mixing bowl using your electric mixer at a low speed, mix together the eggs, flour, sugar, and salt. Slowly add in the warm milk and melted butter. Pour the batter into a tightly-sealed container to refrigerate for at least 2 hours.
Prepare some sheets of parchment paper or paper towels for cooling the finished crepes as you don’t want to stack them directly on top of each other yet.
Use a nonstick pan over medium-low heat. Add a little butter or oil to make sure the batter doesn’t stick.
Pour about 3 tablespoons of the crepe batter into the pan, and swirl to cover the surface of the pan. Cook approximately 1 minute or just until the bottom of the crepe becomes lightly browned. Use a spatula to help lift the edge, and then use your clean fingers to gently and carefully turn the crepe over and continue cooking for another 15-20 seconds. Remove the cooked crepe and place on parchment to cool.
Repeat this process until you have at least 20 crepes that are uniform in size.
When the pastry cream is cold and firm, make whipped cream by beating the heavy cream until stiff peaks form, fold in 1 tablespoon of sugar, and then fold in the pastry cream.