Make the batter: Sift the flour, sugar, and salt into a bowl. In a separate bowl, whisk the eggs and heavy cream until well blended. Add the egg mixture to the flour mixture and whisk until smooth.

Preheat the oven to 350 degrees F. Grease an oval oven-proof dish or individual dishes, with the butter. Sprinkle the bottom and sides with sugar.

Place the banana slices in the oven-proof dish and sprinkle with cinnamon powder. Pour the batter over the bananas and place in the oven.

Bake for 30 to 40 minutes or until the custard is firm. Remove from the oven and cool for 5 minutes before serving.