Anyone got any good recipes for making your own protein bars?

I got tired of finding good snacks that were high in protein and low in sugar and fat etc, and suddenly thought "why don't I just make my own?" I looked online and found a recipe, tried it, and they basically came out of the oven tasting like cardboard texture-wise... I could have used them as doorstops! So does anyone have a recipe they use for making their own protein-rich bars/cakes etc that are also healthy in terms of sugar and fat content?? (Using whey protein I would expect, mine is chocolate mint flavour) Thanks in advance!