For the crepes:

1. Pour flour and salt in a large bowl and make a well in the center. Add the eggs, the melted butter, and the optional sugar if desired. Whisk vigorously starting from the center, and slowly start to pour in a little milk, mixing as you pour, to keep the batter smooth. Pour in the rest of the milk until it looks smooth. Cover the bowl and let sit for 2 hours.*
2. Heat a 15 cm/6-inch crepes pan and grease with oil using a piece of paper towel. Pour in a ladle of the batter by tilting the pan in all directions to distribute the dough well. Heat until the surface is cooked, then flip the pancakes and cook the other surface for about a minute, or until the crepe becomes lightly blonde. Repeat with the remaining batter.
3. Stack the crepes onto a plate, and cover with foil until ready to use.

For the homemade salted caramel sauce:

1. Add sugar to a large heavy bottom saucepan in a thin layer, with just a few drops of lemon juice. Heat over medium heat without stirring or touching.
2. When the sugar is browning slightly underneath, use a wooden spatula to stir very gently in these “sugar pockets” in small circles. Little by little, these pockets of sugar will turn into caramel sauce and become larger. Continue until sugar is completely melted and lightly brown in color (the temperature should be around 300°F or 150°C).
3. Remove from heat and add the heavy cream (previously heated for 30 seconds in the microwave) in 2 or 3 additions, stirring constantly until fully incorporated. Add the cold dice butter, sea salt, and stir until smooth and creamy.**
4. Garnish the crepes with the salted caramel sauce and roll them up tightly. Place onto a plate, cover with cling film and place in the freezer to harden a little bit and allow a clean cut later on. Meanwhile, prepare the caramelized apples.

For the caramelized apples:

1. In a large pan with a heavy bottom, melt the apples with butter on medium-high heat. Cover with sugar and allow the apples to be coated with the caramel sauce, stirring gently from time to time. Add a splash of Calvados if desired.
2. When ready, remove the pan from the heat and add just a few drops of lemon juice to prevent the caramelized apples from hardening.
3. Remove the rolled-up crepes from the freezer, slice the tips and discard them (or eat them right up!). Slice the remaining rolls in 3 to 4 pieces each (they don’t have to measure exactly the same; the irregularity in the slices is what creates a beautiful visual) and place them upright in each plate, in a sushi-like posture.
4. Add caramelized apples around the crepes rolls and drizzle some salted caramel sauce here and there. And voilà!