Preheat the oven to 350 degrees. Spray a 9-inch by 5-inch loaf pan with cooking oil spray. Fit a piece of parchment paper in the bottom of the pan going across the long end; have the ends come up and sides and have about a 1 inch overhang. Spray it with the cooking oil spray. Set aside.
Combine the butter and sugar in the bowl of a stand mixer fitted with the paddle attachment. Mix on medium speed until the mixture looks light and fluffy. Add one egg at a time, beating well each time. Add the bananas, vanilla, and rum to the mixture and mix well on medium speed.
In a small bowl, sift together the flour, baking powder, salt, and cinnamon. With the mixer running on its lowest speed, add the flour mixture to the bowl little by little, until just combined.
Add the toffee pieces and one cup of chopped pecans to the batter and mix until just combined. Pour the batter into the prepared loaf pan and spread with a spatula to level. Sprinkle the reserved pecans on the top of the loaf.
Put the pan into the preheated oven and bake for about 1 hour. The bread is done when a toothpick inserted in the center comes out clean.
Remove the bread from the oven let cool for 10 minutes. Remove the bread from the pan using the parchment paper if necessary, peel the paper off and put the bread back into the pan. Poke a lot of little holes across the top of the bread using a toothpick.
While the bread is cooling, heat the water, rum, butter, brown sugar, cinnamon, and sliced banana together in a small saucepan, boil for one minute and then remove from heat, scoop out the pieces of banana and set aside.
When the bread has cooled slightly, slowly pour the sauce across the top of the bread, letting it soak into the holes with the excess running back into the pan. Let the bread soak for at least five minutes and then remove the bread to a plate; slice and serve warm.
Those banana pieces? Pop them in your mouth for a treat; you deserve it!