Prepare the salted caramel: In a medium saucepan over medium heat, melt the sugar until golden amber. Remove from heat and stir in butter until melted. Gradually mix in cream and salt, then let cool.
Preheat oven to 350°F (175°C) and grease a loaf pan.
In a bowl, whisk flour, baking soda, cinnamon, nutmeg, and salt.
In another bowl, cream softened butter and sugar until fluffy. Add eggs one at a time along with vanilla.
Alternate adding dry ingredients and buttermilk to the creamed mixture until just combined.
Fold in mashed bananas gently.
Layer half of the batter in the prepared pan, drizzle with half of the cooled caramel, add remaining batter, and top with more caramel.
Use a toothpick to swirl the mixture lightly.
Bake for 55-65 minutes or until a skewer comes out clean.
Cool in pan for about 15 minutes before transferring to a wire rack.