Old Fashioned Banana Cake

butter ((75 grams))

brown sugar (not packed) ((150 grams))

vanilla ((3.15 grams))

egg

mashed bananas (ripe)

cake flour ((187.50 grams))

baking powder ((5 grams))

baking soda ((3.5 grams))

salt ((1.4 grams))

sour milk ** ((30 grams))

butter ((56.5 grams))

+ 1 tablespoon cream cheese ((63 grams))

icing / powdered sugar ((312.5 grams))

vanilla ((1.05 grams))

cream ((28.5 grams))