01 - Melt the butter in a saucepan over medium heat. Continue cooking, swirling occasionally, until it foams and golden-brown bits form at the bottom, about 5–7 minutes. Pour into a bowl and let cool for 10 minutes.
02 - Preheat oven to 350°F (175°C). Grease and line a 9-inch round cake pan or loaf pan with parchment paper.
03 - In a medium heavy-bottomed saucepan, heat the sugar over medium heat, stirring constantly until fully melted and amber in color. Carefully add the cubed butter — it will bubble vigorously — and whisk until melted. Slowly drizzle in the cream while whisking continuously. Remove from heat and stir in the flaky sea salt. Cool to room temperature.
04 - In a bowl, whisk together the flour, baking soda, and salt. Set aside.
05 - In a large bowl, combine the cooled browned butter, granulated sugar, and brown sugar. Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract, mashed bananas, and sour cream until smooth.
06 - Add the dry ingredients to the wet mixture, folding gently just until combined. Do not overmix.
07 - Spread half the batter into the prepared pan. Drizzle with half the cooled salted caramel and swirl gently with a knife. Repeat with the remaining batter and caramel.
08 - Bake for 45–55 minutes, or until a toothpick inserted in the center comes out clean. Cool in the pan for 10 minutes, then transfer to a wire rack.
09 - Serve warm or at room temperature. Drizzle with additional salted caramel and top with sliced banana or toasted chopped pecans as desired.