Step 1

Preheat the oven to 400°F (180°C) and grease and line the base of a 9½ inch round cake tin. (If making a double-layered cake, use 2 tins and double the quantity of cake mixture and frosting).

Step 2

Put the nuts and pineapple in a blender or food processor and pulse briefly until finely chopped.

Step 3

Sift all the dry ingredients, up to and including the salt, into a mixing bowl, then stir until combined and set aside.

Step 4

In a separate bowl, add the bananas, coconut oil or butter, reserved pineapple juice, vanilla, vinegar, and egg, if using. Whisk until combined, then add to the dry ingredients with the pecan and pineapple mix. Briefly stir until combined, but do not over-mix the cake batter.

Step 5

Spoon the mixture into the cake tin and level the top. Bake for 30 minutes, or until a skewer inserted into the middle comes out clean. Leave to cool for 5 minutes, then turn out of the tin onto a rack to cool completely.

Step 6

Meanwhile, make the frosting. Beat the butter and cream cheese together until light and fluffy. Add the salt and vanilla, then stir in the icing sugar, a little at a time, to make a thick, spreadable icing. Spread the frosting over the top of the cake (or half over each cake if making 2). Sprinkle with the coconut flakes and pecans.