Creating high-protein food for hiking
I normally make cookies using 1 cup almond butter, 1 egg, 1 c. sugar, perhaps you can substitute some of the sugar for protein powder and see how it goes? Now I'm somewhat interested in trying that myself!

According to nutrional data it looks like protein powder and egg whites have the most amount of protein in them, the list Foods highest in Protein may help.

Update: I ended up making a new batch of cookies, and they turned out great. Used 1c. almond butter, 1 egg, 3/4 c. double chocolate whey protein powder, 1/4 c. sugar 1 tsp baking soda. Bake at 350 for 12 minutes. They are a bit soft, but hold together well and aren't too crumbly until eaten, they seem to hold better after they are a day old.