Preheat your oven to 350°F (175°C). Grease a square baking pan or line it with parchment paper for easy removal.

In a large mixing bowl, mash the ripe bananas using a fork until smooth.

Stir in the almond butter until well combined with the mashed bananas. I recommend using a whisk to ensure that everything is evenly combined.

Sift in the cacao powder to avoid lumps and mix until the batter is smooth and all ingredients are fully incorporated.

If using, add the vanilla bean powder for extra flavor. Fold in the chopped walnuts for added texture. You can also add a pinch of salt if you love that chocolatey nutty salty flavor combination.

Pour the brownie batter into the prepared baking pan, spreading it evenly. Slice a banana in half lengthwise and press the two pieces lightly into the top of the bananas.

Bake in the preheated oven for approximately 20-25 minutes or until a toothpick inserted into the center comes out mostly clean with a few moist crumbs.

Allow the brownies to cool in the pan for about 10 minutes, then transfer them to a wire rack to cool completely. Once cooled, cut into squares or bars.

Serve these delightful and nutritious vegan brownies on their own or with a dollop of your favorite vanilla ice cream or chocolate sauce.