Prepare the salted caramel by melting sugar in a saucepan over medium heat until amber in color. Add butter, stir until melted, then slowly mix in heavy cream and salt. Let cool.
Preheat oven to 350°F (175°C) and grease a loaf pan.
In one bowl, whisk together flour, baking soda, cinnamon, nutmeg, and salt.
In another bowl, cream softened butter and sugar until fluffy. Add eggs one at a time, then mix in vanilla.
Gradually combine dry ingredients with wet mixture alternating with buttermilk until just mixed.
Fold in mashed bananas gently.
Pour half of the batter into the prepared pan; drizzle half of the cooled caramel over it. Add remaining batter and finish with the rest of the caramel.
Bake for 55-65 minutes or until a skewer comes out clean. Cool before serving.