Preheat oven to 350 degrees. Grease pan 9×5 inch loaf pan with cooking spray; set aside
In a small bowl, mix together mashed bananas a potato masher or in a blender. Then mix in eggs, rum, sour cream and vanilla until smooth; set aside
Blend together all the dry ingredients using a hand mixer- sugar, baking powder, baking soda , nutmeg and salt
Then, add butter to the dry mixture until fully incorporated, gradually add wet ingredients
Continue mixing for about 2 minutes until dry ingredients are fully incorporated.
Scrape down sides and batter into the pan and spread evenly
Bake for 55 to 60 minutes, or until a toothpick inserted in the center comes out clean
Cool, and then remove it from the pan to serve
As the cake cools
Add butter, brown sugar, and heavy cream in a medium saucepan over medium heat.
Then bring to a boil, stirring the mixture continuously.
Reduce heat to simmer and let it cook for about a minute more without stirring.
Finally remove from heat and whisk in the confectioners' sugar. Allow the glaze to cool and let it thicken up may take about 5-10 minutes.
You can start spreading glaze over the cake with a spoon before serving.
Glaze can be easily warmed up in the microwave for about 10 minutes.