4teaspoonsarrowroot powder, (you can omit but the frosting will be looser)
⅛teaspoonfine salt
1teaspoonvanilla extract
4 to 5 cups (500 to 625 grams)powdered sugar, (icing sugar in the UK)
INSTRUCTIONS
For the cake
Preheat oven to 350°F (176°C) and grease a 9 x 13 inch ovenproof dish with some oil or vegan butter.
Peel the bananas and put them in a large bowl. Mash them up really well until they are a smoothish puree.
To the bananas add the sugar, vinegar, vanilla, milk, oil, salt, cinnamon and nutmeg. Whisk it all up until well combined.
Add the flour, baking powder and baking soda to the wet ingredients and stir them together gently to combine. Don't beat hard or use an electric whisk, and stop as soon as there is no dry flour visible anymore.
Pour into the prepared pan and bake for approximately 40 minutes, or until golden brown, coming away from the sides slightly and a skewer/toothpick inserted into the middle comes out clean. The time will vary depending on your oven and the dish/pan you are cooking the cake in. 40 minutes cooking time is based on using a glass dish. If you use metal it will likely be ready a little quicker so check from 30 minutes.
Remove from the oven and leave to cool in the dish on a wire rack.
For the frosting
Add the vegan butter to a large bowl and beat it with an electric mixer on a medium high speed until soft and fluffy.
Add the cream cheese and beat again until combined and smooth but don't over-beat. As soon as it's combined stop.
Now add the arrowroot powder, salt, vanilla and about 2 cups of the powdered sugar. Beat on the lowest speed for about 20 seconds until the powdered sugar has stopped flying around, then add another 2 cups. Beat again on low until it's mostly combined then turn the speed up to medium high again and beat until smooth and creamy, scraping down the edges with a spatula as needed to get any dry powdered sugar off the sides and into the mix.
Add the remaining powdered sugar to thicken as needed. Using it all makes the frosting much easier to handle, spread and pipe.
Do not be tempted to add any more liquid to the frosting at any stage because it will become too runny. Once done, cover the bowl and put in the fridge until needed.
Slather generously all over the top of the completely cooled banana cake.
NOTES
* It's important that the bananas are really ripe, soft, and spotty. If they aren't ripe enough there won't be enough moisture in the batter and your cake won't taste as good. To store - Cover tightly, and store in the fridge for up to 6 days. The cake also freezes really well without the frosting. Bake, allow to cool completely, then wrap the entire thing (dish as well as long as it's freezer-safe) very tightly and freeze for up to 3 months. Defrost in the fridge overnight then frost.