Preheat oven to 350 degrees F.

Line an 8x8" square pan with foil or parchment paper. Spray with nonstick spray

In a bowl mix the flour, salt, and baking soda

In another bowl mix the butter and sugars using a mixer on medium-high speed until the butter becomes fluffy. About 3 minutes

Add the banana, egg, sour cream and vanilla. Mix well

Finally, add the flour mixture slowly

Pour the batter into the pan and bake for 35-45 minutes or until a toothpick inserted in the middle of the cake comes out clean.

Remove from oven and let it cool before frosting

For Frosting

Place the butter on a pot

Melt over medium heat

When the butter starts boiling, reduce heat to medium-low and stir frequently to prevent from burning

When the butter starts to smell nutty or you see the milk solids getting darker, remove from heat

Toss the brown butter, sugar, salt, and heavy cream in the bowl of a mixer

Mix on medium-high speed for 4-5 minutes or until the frosting becomes creamy and airy. If the mixture seems too stiff, add more cream

Frost the top of the cake and cut into squares

Enjoy!