Place butter and brown sugar in a large saucepan or high-sided skillet over medium-high heat. Stir until butter is melted and mixture is bubbly.

Add mashed banana and continue to boil for about 5 minutes to further develop the caramelized flavor.

Remove from heat, then stir in rum (be careful as it will sputter).

Transfer to a heat proof bowl or the bowl of a stand mixer fitted with the paddle attachment and let cool to lukewarm (under 100 degrees when measured on an instant read thermometer; it should feel only warm to the touch, not hot). This could take upwards of 30 to 45 minutes.

Preheat oven to 350 degrees F.

Lightly butter an 8.5-by-4.5-inch loaf pan; line the bottom and two sides with a strip of parchment paper.

Once the banana mixture is cool, beat in eggs, one at a time, until completely incorporated.

Whisk together flour, baking soda, cinnamon and salt, then add to banana mixture and stir until almost incorporated.

Add pecans (reserve a small handful to sprinkle on top, if desired) and fold in until evenly distributed and no streaks of dry flour remain.

Pour batter into prepared loaf pan, and sprinkle with reserved pecans.

Bake for 55 to 65 minutes or until deep golden brown on top and a toothpick inserted in the center comes out with just a few moist crumbs attached.

Let cool on a wire rack for at least 30 minutes before lifting the loaf out of the pan.

Slice using a serrated knife and serve, ideally while still slightly warm.