Preheat the oven to 325°. Butter a 9-fade spherical cake pan and line it with parchment paper; butter the parchment paper. Mud the pan far and big with flour, tapping out any excess. In a medium bowl, flow the flour with the baking powder, baking soda and salt.
In a natty bowl, using a handheld electric mixer, beat the butter and sugar at medium-high flee except gentle and fluffy, about 3 minutes. Beat within the egg yolks and vanilla extract. Add the mashed bananas and beat the combination except at ease. Add half of of the dry ingredients and beat at low flee except the batter is moistened. Beat in half of of the buttermilk, then add the final dry ingredients and the final buttermilk.
In a medium bowl, beat the egg whites at medium-high flee except company peaks execute. Beat one-fourth of the egg whites into the batter at low flee. The employ of a rubber spatula, fold within the rest of the whites except no streaks dwell. Predicament the batter into the ready pan and at ease the tip. Bake the cake for roughly 40 minutes, except the tip is golden and springy and a toothpick inserted within the heart comes out natty; the tip will be very a tiny cracked. Let cool within the pan for quarter-hour, then invert the cake onto a rack to cool entirely. Peel off the parchment paper.
In a medium bowl, beat the mascarpone with the confectioners’ sugar at medium flee except the frosting is gentle and fluffy, about 2 minutes. The employ of a natty serrated knife, decrease the cake horizontally into 3 layers. Build the tip layer, decrease facet up on a cake plate and unfold with one-third of the mascarpone frosting. Put together half of of the bananas in a single layer on the frosting. Top with the center cake layer. Duvet the layer with one other third of the frosting and high with the final bananas. Duvet with the bottom cake layer, decrease facet down, and frost the tip. Refrigerate the cake for no longer decrease than half-hour sooner than serving.
The baked and cooled cake can also additionally be tightly wrapped in plastic and refrigerated for 3 days or frozen for up to 1 month. The assembled cake can also additionally be made earlier within the day and refrigerated.
Cooking Membership Tip: Stick so a lot of toothpicks spherical the circumference where you imply to separate the cake into layers. Then with a serrated knife or portion of taut, unwaxed, unflavored dental floss, cut the cake horizontally (using the toothpicks as a files), gently sawing backward and forward to diminish.