In a small bowl, whisk together the egg white, granulated sugar, milk and vanilla extract until well combined.
Add the pinch of salt, flour and melted butter and whisk until smooth.
Lightly spray a non-stick skillet with non-stick spray and then scoop 1 1/2 tbsp of batter onto the center of the cold pan.
Use an off-set spatula or the back of a metal spoon to spread the batter out into a 4 inch circle.
Place the pan over low heat and cook for 4-5 minutes, or until the bottom is golden brown and then top is set.
Flip the cone like a pancake and continue to cook for about another minute, until the other side is golden brown.
Remove the pan from the heat and immediately place the cone into the slots of a cookie cooling rack, draping it over 2 bars to create the taco shell. You can also use the binding of a thick book, an empty paper towel roll, the handle of a wooden spoon etc to achieve the same shape. The cone will start to harden almost immediately, so you need to work fast. The cone will also be very hot, so use a clean towel as a barrier between your hands and the cone.
Repeat the above steps in a new, cold skillet. Continue rotating skillets and only using cooled down skillets to make the next sugar cone shells. Repeat until all of the batter has been used and all of the sugar cone shells are made.