Start by pre-heating the oven to 180 celcius, then peel the sweet potatoes. Cut them into chunks and place into a steamer for about twenty minutes, until they become really soft.
Once they are perfectly soft and beginning to fall apart remove them and add them to a food processor with the pitted dates.
Put the remaining ingredients into a bowl, before mixing in the sweet potato date combination. Stir well.
Place into a lined baking dish and cook for about forty-five to fifty minutes, until you can pierce the brownie with a fork and bring it out dry. Remove the tray and allow it to cool for about ten minutes – this is really important as it needs this time to stick together!
While the brownies are cooking make the icing by simply melting all the ingredients together and stirring well, then place in the freezer for 15 minutes and then the fridge for 15 to firm up a bit.
Remove the brownies from the tray and leave to cool completely before icing otherwise your icing will melt! Spread the icing on top, cut into squares, dig in and enjoy!