Preheat the oven to 350 degrees F and grease a 10-inch springform pan with baking spray, then set it aside.
In a medium bowl, combine flour, baking powder, baking soda, ground cinnamon, and salt. Set aside.
In a large bowl, beat butter and sugar using a hand mixer until light and fluffy.
Slowly add the eggs one at a time, mixing well after each addition.
Add vanilla extract, yogurt, and mashed banana, then beat for a couple more minutes.
Gradually add the flour mixture in batches, mixing until everything is well incorporated.
Stir the chopped walnuts into the cake batter and fold them in.
Transfer the cake batter to the prepared springform pan and smooth the top.
Bake the cake for 55-60 minutes until a toothpick inserted in the center comes out clean.
Once done, allow the cake to cool for 20 minutes on a wire rack. Slowly remove the springform pan by loosening the sides.
Meanwhile, prepare the frosting: In a medium bowl, add the cream cheese and butter, then beat them together for 2-3 minutes using a hand mixer.
Add the vanilla extract and gradually add the confectioners sugar in batches until the frosting turns light and fluffy.
Top the banana walnut cake with the prepared cream cheese frosting and sprinkle the chopped walnuts on top.
Slice and serve the cake.