Preheat the oven at 180 C or 350 F. Grease and dust a 7 or 8 inch round cake tin or 9 X 5 loaf pan or 8 inch square cake tin.
Peel and roughly chop the bananas and place them in a large mixing bow
Chop walnuts and dark chocolate.
Mash the chopped bananas well.
To the mashed banana, add 1/2 cup oil to it.
Next add 1 teaspoon vanilla bean powder or vanilla extract.
Add 1/3 cup sugar.
Finally add 1/4 cup yogurt, 1/4 cup almond milk.
Whisk everything well until the mixture turns light and pale. Place a sieve over the bowl. Add 1.5 cups flour, 1.5 teaspoons baking powder, 1/4 teaspoon baking soda and salt.
Mix and sift the dry ingredients into the wet ingredients. Mix the flour mixture well yet gently. Do not over mix the batter. A few streaks of flour is ok.
Now add the chopped chocolate and walnuts.
Mix gently. Pour the banana cake batter evenly into the prepared tin. Tap gently.
Place the halved walnuts all over.
Bake in the preheated oven for 30-35 minutes. The cake is done when the top is evenly browned and a tester or toothpick inserted comes out clean from the center.
Let the cool cake in the pan for 5 minutes. After 5 minutes, remove the cake to wire rack and cool completely.
Slice into squares and serve vegan banana cake warm.