Preheat the oven to 325°F (no fan). Line a 9 x 13-inch pan with parchment paper overlapping up two sides.

In a medium bowl, whisk together the dry ingredients (flour, baking powder, salt, cinnamon). Set aside.

In another large bowl, whisk the eggs until no streaks of whites remain. Add the bananas to the eggs and whisk to combine.

Add the sugars and vanilla to the banana mixture. Whisk until smooth then pour in the butter. Whisk until combined. Once you add it to the butter, the mixture will thicken slightly.

Add the flour mixture to the bowl with the wet ingredients and stir just to combine. Just like with cookies, you don’t want to over-mix the batter at this stage.

Pour the banana batter into the prepared baking dish, spread out with an offset spatula and bake in a preheated oven for 25 minutes. The top will begin to brown. The very center of the cake will still appear a little glossy. A toothpick will come out with a few clinging crumbs.

Cool completely (no need to use a wire rack) and prepare frosting while the cake cools.

In the bowl of a stand mixer fitted with the paddle attachment or in a large bowl with an electric hand mixer, beat together softened butter and cream cheese until smooth. It is important that both are softened or the resulting buttercream will be lumpy.

Add the powdered sugar and beat until smooth. If your confectioners’ sugar is unusually lumpy, sift it into the cream cheese mixture. Add the vanilla extract and lemon juice and beat to combine.

Dollop the frosting on the cooled cake and then spread with an offset spatula. You can make it perfectly smooth or swirl it decoratively.

Slice into cake and serve.