1. Preheat your oven to 350°F (175°C). Grease and flour a 9×13 inch pan.
2. In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
3. In a large bowl, cream the butter and sugar together until light and fluffy, about 3 minutes.
4. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
5. Mix in the mashed bananas and sour cream until well combined.
6. Gradually add the dry ingredients to the banana mixture, gently folding until just combined. Do not overmix!
7. Fold in the chopped walnuts.
8. Pour the batter into the prepared pan and smooth the top with a spatula.
9. Bake in the preheated oven for 35-40 minutes or until a toothpick inserted into the center comes out clean.
10. While the cake cools, prepare the frosting by whipping the heavy cream, confectioners’ sugar, and vanilla extract together until soft peaks form.
11. Once the cake is completely cool, spread the frosting evenly over the top.

Remember, the key here is to fold the ingredients gently. My dad always said, “Let the batter breathe, and it will rise to the occasion.”