Peel the bananas and remove any strings. With a knife on parchment paper, roughly chop the ripe bananas; set aside.

Place the butter over high heat in a large heavy metal pot. Brown the butter and add the sugar and brown sugar. Continue to cook, stirring constantly, until it reaches a beautiful dark caramel color. Add the bananas and cook 3 to 4 minutes more until the bananas have all broken down.

Remove from the heat and add the Meyers Rum (use caution, rum is flammable). Stir to combine, place back on the heat, and continue to cook, stirring constantly, until all the liquid is gone, about 2 minutes.

Remove from the heat, stir in the lemon juice, and immediately puree with a food processor. Pour out onto a hotel pan or plastic-lined sheet tray, cover with plastic, and allow to cool.

Preheat oven to 375 degrees. Adjust the rack to the lower third of the oven. Lightly coat eight 6 to 8 ounce ramekins with the melted butter; then lightly but completely dust them with the sugar. Place the ramekins on a baking sheet.

On speed 3 of a standing mixer fitted with the whip attachment, whip the egg whites for about 30 seconds, or until soft foam appears. Add the cream of tartar; whip to soft peaks, streaming in the sugar slowly. Continue to whip to medium stiff peaks. Fold the whites into the bowl containing the banana and chocolate mixture. Spoon into the prepared ramekins, filling them to the rim. Smooth the tops with a metal spatula. Gently run a paring knife around the inside edge of each ramekin. This creates a wall of air that helps the soufflé rise up straight.

Bake in the oven for approximately 12-15 minutes, or until tall, golden brown, dry on the edges, and creamy in the center. Serve immediately.