Preheat your fan oven to 160°C (325°F) or 175°C (350°F) if you're not using a fan assisted oven.
In a bowl of a stand mixer, fitted with a paddle attachment, sift together flour, salt, cinnamon and baking powder. Add the sugar and set aside - these are your dry ingredients.
Whisk together mashed bananas and eggs. Add the sour cream and vanilla extract. These are your wet ingredients.
Add softened butter to dry ingredients and mix on medium-low speed until you get crumbly, sand like texture.
Add the wet ingredients to butter/flour mixture and beat on medium-low speed until combined, approx. 30-60. Scrape down the bowl while mixing to ensure everything is thoroughly combined. In the end, fold in the chocolate chips using a spatula, which you previously coated with a little flour, to prevent them falling to the bottom.
Fill a 10 inch (25 cm) bundt pan with cake batter and bake for 40-50 min or until skewer inserted in the middle comes out with a few moist crumbs.
Once it's done, leave it to cool for 15 minutes on a wire rack before turning the cake upside down to cool, still in the pan, for another 15-20 minutes before removing it to cool completely.
Place finely chopped chocolate in a bowl. Bring heavy cream just barely to a simmer and pour over chopped chocolate. Cover it with a plate and leave it 1-2 minutes. Stir with a spatula until combined and smooth.
Once the cake is cooled, put it on a serving plate and pour over slightly cooled chocolate ganache. Top with roasted hazelnut crunch or fresh raspberries.
Not all ovens are the same. I suggest you check the cake after 35 minute mark and then adjust the time accordingly. Get to know your oven! :)
If you don't have a stand mixer, you can use an electric hand mixer.
The more ripe banana is, the better flavour you'll have.
The cake is best when eaten at room temperature. Keep it in an airtight container or double wrapped in cling film to keep it fresh.
If you still don’t own one, I advise you to buy a kitchen scale – they’re cheap and easy to use, and always guarantee the same results in baking! :)