01 -
Preheat the oven to 175°C. Line a 33x23 cm baking dish with parchment paper.
02 -
In a large bowl, combine softened butter with sugars and mix until just combined. Whisk in the eggs and vanilla, followed by the mashed bananas. Combine the dry ingredients together and add to the wet mixture, mixing to incorporate. Set aside.
03 -
Using a double boiler, melt butter with dark chocolate over simmering water. Allow to cool slightly. In a stand mixer, whisk together eggs, sugars, and vanilla on high speed until light and creamy (about 4-5 minutes). Fold in the cooled melted chocolate using a spatula. Sift together the flour and cocoa powder, and gently fold into the wet brownie mixture.
04 -
Spread half the banana bread mixture into the prepared baking dish. Dollop large spoonfuls of brownie batter across the surface, then spread the remaining banana bread mixture in between. Swirl gently with a spoon or knife to create a marbled effect. Dollop additional brownie batter over the top, if desired.
05 -
Bake for 30-35 minutes. To ensure it is fully cooked, insert a toothpick into the center; it should come out clean. For a slightly gooey texture, remove after 30 minutes and allow to cool in the pan.
06 -
Allow to cool completely before slicing. Serve and enjoy!