In a blender or a large bowl place the eggs, flour, sugar, cocoa powder and milk. Blend together. If using a large bowl, blend together with an immersion blender. Alternatively you can whisk the mixture together but it may be not be as smooth. Add in the melted butter at the end and blend for another minute to make sure it's incorporated.
Heat a large non stick skillet over medium heat. Allow the skillet a few minutes to fully heat up. Add a ladle full of crepe batter(how much will depend on how big your pan is, use just enough to cover the pan otherwise your crepes will be thick) to the pan and swirl so that the batter covers the entire bottom of the pan. Once the batter is evenly distributed return the pan to the burner and let cook for 1-2 minutes.
When ready to flip the edges should look dry and may pull away from the edge of the pan. Using your hands and a flipper, gently lift the crepe from the pan and flip over. Cook on the other side for about 30 seconds and place on a plate or on the counter with a lid to keep it from drying out.
Cook the rest the same way and enjoy!
I added about a tbsp of extra dark cocoa powder to these in place of regular cocoa simply because I was running out. Either way these are wonderful but if you use all regular cocoa yours may not be as dark as these.