Nut-free.Use sunflower seed butter or tahini.
Sea salt.Sprinkle the bars with coarse sea salt before slicing.
Mix-ins.Add dried fruit (I like raisins or cranberries), chopped nuts, or shredded coconut for added texture.
Nut butters.I love the combination of peanut butter and chocolate, but you could substitute any nut butter. I also had luck withalmond butterand cashew butter.