Preheat the Oven: Preheat your oven to 275°F (135°C). Grease and flour a 9×13 inch baking pan.

Prepare the Bananas: In a small bowl, mix the mashed bananas with lemon juice and set aside.

Mix Dry Ingredients: In a medium bowl, whisk together flour, baking soda, and salt.

Cream Butter and Sugar: In a large mixing bowl, cream softened butter and granulated sugar until light and fluffy.

Add Eggs and Vanilla: Beat in the eggs one at a time, ensuring each is fully incorporated. Stir in vanilla extract.

Combine Wet and Dry Ingredients: Gradually add the flour mixture to the creamed butter mixture, alternating with buttermilk. Mix until just combined. Stir in the banana mixture.

Bake the Cake: Pour the batter evenly into the prepared pan. Bake for about 70 minutes, or until a toothpick inserted in the center comes out clean.

Cool the Cake: Allow the cake to cool completely in the pan on a wire rack before adding the frosting.

Make the Caramel Frosting: In a medium saucepan over medium heat, melt brown sugar and butter, stirring constantly. Add heavy cream and bring to a gentle boil. Remove from heat and beat in powdered sugar and vanilla extract until smooth.

Frost the Cake: Once the cake is fully cooled, spread the caramel frosting evenly over the top.

Serve: Slice into squares and serve at room temperature.