Step 1

Preheat oven to 350 degrees F (175 degrees C) and line a 12-cup muffin tin with liners.

Step 2

Whisk flour, baking powder, baking soda, and salt together in a bowl.

Step 3

Mash bananas with milk and vanilla extract until smooth.

Step 4

Mix butter and sugar together with a spatula until creamy. Whisk in eggs, 1 at a time, then whisk in the banana mixture. Add walnuts, chocolate, and the flour mixture. Mix batter with a spatula until no dry spots remain.

Step 5

Fill muffin cups to the top with batter, then distribute excess batter as needed. Tap pan against the counter to expel any air bubbles.

Step 6

Bake in the preheated oven until tops are lightly browned, about 25 minutes. Let cupcakes cool to room temperature, at least 20 minutes.

Step 7

Pour hot cream over chocolate chips in a bowl. Let sit for a few minutes, then whisk, increasing speed gradually, until color is uniform. Spread ganache over the cooled cupcakes and garnish with banana chips. Refrigerate to firm up the frosting, if desired.