• Preheat the oven to 175C (345F) and line 2 x 8 inch (20cm cake tins or one 33cmx23cm/ 13"x9") slab cake tin with baking paper (see "variations" above for different size cake tins.
• In a medium sized bowl, sift flour, baking powder, baking soda, salt and cinnamon. Whisk to combine and set aside.
• In a larger bowl, beat butter (with a hand held mixer or stand mixer with paddle attachment) until creamy. Gradually add the brown and white castor sugar and continue beating until it is light in colour and fluffy in texture. With the mixer still on, slowly add the oil and continue beating until combined.
• Add bananas and beat well until well combined. Add eggs and vanilla extract to the butter-banana mixture and mix until just combined. Add half the flour mixture and fold about 5 times. Now add ½ of the buttermilk and fold again. Add the rest of the flour along with the remaining half of the buttermilk and gently fold until combined (combining the ingredients this way helps to keep the batter light and prevents too much gluten from forming).
• Divide the cake batter among the two cake tins (or one 33cmx23cm/ 13"x9") slab tin)and bake for 30 – 40 minutes or until a skewer comes out clean (or with a few loose crumbs). Leave to cool in cake tins for 5 minutes before inverting on a cooling rack.
• Once completely cool, level the cakes with a serrated knife (optional - you can skip this if baking in a slab tin and ice slab once cool). If decorating two 8" layers, place one cake on a cake board and using a off-set spatula, spread ⅓ cup of frosting on the cake. Place the other cake on top and apply the rest of the mascarpone frosting. Decorate as desired and serve.

To make the Chocolate Mascarpone Frosting:

• In a small bowl, mix the mascarpone and cocoa powder until well combined, set aside. In a separate bowl, beat the cream, icing sugar and vanilla until soft peaks form. Mix three tablespoons of the cream to the mascarpone mixture to loosen it up. Add mascarpone to the remaining whipped cream and beat together until combined (be careful not to over-mix, over-mixing will make the cream ‘grainy’).