Peel the sweet potatoes. Cut them into chunks and place into a steamer for about 20 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 dates. Blend until a smooth, creamy mix forms.
Put the remaining ingredients into a bowl before mixing in the sweet potato and date combination. Stir well.
Place the mix into a parchment paper–lined baking dish and cook for 20–30 minutes, until you can pierce the brownie cake with a fork and bring it out dry. Remove the dish from the oven and allow it to cool for about 10 minutes. This is really important, as the brownies need this time to stick together!
If you don’t have any raw cacao powder, then you can use conventional cocoa powder, but you’ll need to at least double the quantity.