Sourdough sweet potato brownie

I'm really pleased with this recipe, and so are my family.
I'm ecstatic to make a treat that's actually good for them, and it tastes great. Woo hoo!
It is low in grains, high in fruit and vege's, and no added sugar (apart from the sugar in the dark chocolate used in the icing).

Ingredients

300g sweet potato, peeled, diced and steamed.

1/2 cup buckwheat flour

1/3 cup dessicated coconut

1/3 cup spelt flour

1/3 cup sourdough starter

3 Tablespoons carob powder

1 Tablespoon cocoa powder

3 Tablespoons butter, melted

1 egg, beaten

1 banana, mashed

1/2 cup blackcurrants (mine are frozen)

1 teaspoon baking soda

Icing

50g 70% dark chocolate

3 Tablespoons cream

1. Mash the steamed sweet potato well, and let cool.

2. Add the next 8 ingredients, mix well and cover. Leave for 2 - 24 hours.

3. Heat your oven to 180 degrees.

    Line a 20x20cm cake tin with baking paper.

    Add the last 3 ingredients, and mix through the batter.

    Pour into your prepared tin and bake for 40 minutes.

4. Check that your brownie is cooked in the middle, and a sharp knife comes out clean.

    When cooked remove from pan, and let cool.

5. Melt the dark chocolate in a small bowl over hot water.

    When melted add the 3 Tablespoons of cream and mix well.
    Spoon the icing over the brownie and spread with a knife.

If you are local, I get my blackcurrants frozen from Putiputi ra in Whangarei.