01 -
In a medium microwave-safe bowl, melt the chopped chocolate in the microwave in 30-second intervals, stirring between each interval. This process should take about 1½ to 2 minutes total. Stir well until completely smooth and set aside.
02 -
Place the banana chunks in a food processor and process until smooth and creamy, forming a paste-like consistency. Add the vanilla extract and blend again until the mixture is homogeneous.
03 -
Pour the melted chocolate into the food processor with the banana mixture. Process until everything is fully combined and forms a homogeneous brownie batter.
04 -
If using pistachios, transfer the mixture to a bowl and fold them in using a rubber spatula. Do not process the nuts in the food processor as they should remain in pieces for texture.
05 -
Line an 8-inch square cake pan with parchment paper, making sure the edges of the paper overlap the sides of the pan for easy removal later. Pour the brownie batter into the prepared pan and gently shake or tap the pan to level the surface evenly.
06 -
Cover the pan tightly with aluminum foil or a lid, making sure it doesn't touch the batter. Refrigerate for at least 4 hours, or until the brownies are completely set and firm to the touch.
07 -
Once set, hold the edges of the parchment paper and lift to remove the brownies from the pan. Flatten the edges of the paper and cut into 9 even slices. For clean cuts, rinse the knife in hot water and wipe with a clean towel before each cut.
08 -
If desired, dust the brownies with Swerve confectioners sugar using a fine-mesh sieve. Garnish with additional slivered pistachios and fresh raspberries before serving.