Note: this is a recipe from bodybuilding.com.
10 T natural peanut butter
5 egg whites
5 scoops whey protein
2 cups oats (optional: For flavor, cook dry oats in a frying pan until they are toasted)
1/2 C soy milk
Mix the peanut butter and egg whites in a bowl. Microwave on high for 30 seconds, and mix well (so that the mixture appears smooth). Repeat 4-5 times until all traces of egg whites have dissolved into the peanut butter, and your mixture is a smooth consistency.
Gradually add the protein (one scoop at a time) and stir into the mixture. Next, add the soy milk and follow with the oats. Continue mixing until a thick, sticky mixture is present.
Smooth the thick mixture into a 13x9 tray and leave for 20-30 minutes. Cut into 10 equal size bars.