Use your personal favorite! There are lots of chocolate flavored protein powders, and the best one is a matter of personal preference. In our case, we compared three common low-carb brands of chocolate whey protein powder (Cellucor, Quest, and Optimum Nutrition) in a taste test, and Quest was our favorite. Quest is a whey/casein protein mix and you may have different results if you use a pure whey or plant based protein powder. The exact type of protein powder can make a big difference in some recipes, especially when baking. However, because this is a no-bake recipe, we expect it to be fairly accommodating to other protein powders. If you try it with other brands or types of powder, let us know in the comments so readers know which ones to try and which to avoid.