Preheat oven to 350° F. Line a 9 or 10-inch square baking pan with parchment paper and grease lightly, set aside.
In a large bowl, whisk together the flour, salt, baking powder and salt. Set aside. Cream together the butter and sugar on high until light and fluffy. Stir in the eggs and vanilla. Add the dry ingredients and stir until just combined. Transfer into the prepared pan and spread out into an even smooth layer. Bake until golden brown and the center has set, about 25 to 30 minutes. Remove from the oven and allow to cool completely.
To make the bananas fosters topping, place the butter and brown sugar in a large skillet over medium-high heat. Stir until the butter has melted and the sugar has dissolved. Add the cinnamon and liqueur and bring to a simmer. Add the sliced bananas and cook until they’ve softened, about 5 minutes. Add the rum and carefully top the pan into the flame to ignite. Cook until the flames have subsided. (This step is optional and you can just cook until the alcohol has cooked off). Stir in the salt and set off to the side to cool to room temperature.
To make the frosting, cream together the cream cheese and butter until light and fluffy, about 5 minutes. Stir in the powdered sugar and vanilla and beat on high until fluffy. Transfer half of the frosting onto the cooled bars and spread out into an even layer. Transfer the remaining frosting to a piping bag and pipe out a border along the edges of the cookie bars, this will keep the bananas from leaking over the edge. Pour the cooled bananas and caramel in the center and spread out. Chill for 30 minutes to set before cutting into bars and serving.