In a small saucepan, combine 1/2 cup cream, 1 tablespoon butter and 2 tablespoons sugar over medium heat and bring to a boil. Remove from heat and stir in chopped chocolate until smooth. Set aside.
In medium bowl, whip 1/4 cup cream with electric mixer until stiff peaks form. Set aside.
In large frypan melt 1 tablespoon butter over medium heat. Sprinkle 1 tablespoon sugar evenly over surface of pan and cook until it begins to turn golden. Place bananas cut side down in pan and pour rum over bananas. Continue to cook, basting with sauce, until bananas begin to soften.
To serve, place two warm banana slices on a plate, spoon a little rum sauce over the top, drizzle with chocolate sauce and top with whipped cream.