Try replacing an amount of nut butter with an equal amount of coconut butter. The brownie will have a coconut taste.
Chopped nuts or dried berries, like goji berries, add a nice texture too.
Cut the brownies into portions sizes and store in an airtight container in the fridge. You can even freeze them to last even longer which is great if you batch cook.
When you need something a little sweet and naughty you can just take a piece from the fridge and enjoy knowing you are still eating healthily!