Coarsely chop the chocolate and place it in a bowl. Heat the cream in a small saucepan just to a boil, then let it sit for a minute or two. Pour it over the chocolate. Add the cocoa, sugar and salt and stir until the chocolate has melted and the mixture is smooth. Let the chocolate sauce cool slightly.

Split the bananas in half lengthwise. Place the sugar on a shallow plate, then dip the cut side of the bananas into the sugar so that the surface of the banana is completely covered in sugar.

Place the butter in a frying pan over medium-high heat. Place the bananas, sugar side down, into the hot pan. Fry them without turning, 1-2 minutes each, or until they start to turn golden brown.

Spread the chopped nuts on a shallow plate or cutting board. Carefully remove the bananas from the pan and place them on the nuts, fried side down, so that the nuts stick to the surface.

Serve the bananas with a scoop of ice cream. Drizzle the sundae with some of the chocolate sauce and an additional sprinkle of peanuts.