Preheat the oven to 160 C / 320 F. Line a baking sheet with parchment paper.
In a medium bowl, combine the whey protein powder and melted coconut oil together.
Add the hot water and mix well.
Add the salt and mix well.
Place the mixture on the parchment paper and spread it as thin as possible. (I spread into an approx. 14 x 10 inch (35 x 25 cm) rectangle.)
Bake for about 15 minutes or until golden brown and crispy.
Break it into pieces.
The consistency of the mixture may depend on the whey protein powder you use, so if you find the texture of your batter too thick or too thin before placing it on the parchment paper, adjust it by simply adding more coconut oil/water if thick or more protein powder if thin. The mixture should be creamy but a bit runny (see the video) so that it is easy to spread it on the parchment paper as thin as possible (thin enough to be able to see the parchment paper through the mixture). Otherwise the texture will be dry and crumbly on the palate. The thinner, the crispier! Spreading the mixture as thin as possible before baking is the key to success! Also bake well until crispy!
(Comment added on March 7, 2018) Because whey protein powder has a tendency to not dissolve well in very hot liquid, both coconut oil and water are hot, the protein powder may not dissolve completely and get lumpy. So if you melt your coconut oil because it was solid, please make sure that the oil is not very hot when adding. If it is, let it cool a bit OR add tepid water (instead of the hot water that is called for).