In a small measuring cup add milk and lemon juice, mix together and allow mixture to sit for 10-15 minutes to ‘curdle’ and become buttermilk. 

In a bowl fitted with a stand or hand mixer, add butter, light brown sugar and granulated sugar. Beat mixture for 3-4 minutes or until light and fluffy. Add in vanilla extract and beat eggs in one at a time on low speed. 

In a medium bowl mix together sifted flour, salt, cinnamon and baking soda together. Alternate milk and flour mixture to wet batter mixture and mix together until just incorporated. Remove from the mixer and fold in mashed bananas. 

Divide cake batter into cake tins evenly and smooth out the tops. Bake for 30-35 minutes or until a toothpick comes out clean in the center. Allow cakes to cool for 20-30 minutes and then remove from tins and finish cooling on a cooling rack. 

In a heavy bottom saucepan heat sugar on medium heat until melted, about 5-10 minutes. Stir consistently with a wooden spoon and be VERY careful not to burn. The color should be an amber brown. Any darker and you have burned your sugar. Add in butter slowly and stir until melted. Very slowly add in heavy whipping cream.

*Note the butter and cream will splatter and bubble up because they are a different temp to the sugar, so be careful!* 

Continue to boil and stir for another 30 seconds to 1 minute. At this point we are just trying to thicken the caramel. Remove pan from heat add in salt and stir. Transfer caramel to a glass jar and cool completely before refrigerating. To reheat the caramel place jar in microwave for two 30 second increments, stirring after the first.

Beat in caramel sauce until well incorporated. If frosting feels too thin, add in ½ cup powdered sugar at a time and if too thick add in 1 tbsp of heavy cream in.