Spread the Nutella on all your bread slices, then put 2 slices together to make 6 sandwiches. Cut each sandwich into 8 pieces and toss them into a large bowl. Crack your eggs in another large bowl and whisk in the cream, milk, sugar, hazelnut liqueur, vanilla and almond extracts. Pour this mixture over the sandwich cubes. Now, mash your bananas and stir that into the bread cube mixture. Pour into the prepared baking dish. Let stand at least 1 hour and up to 2 hours, occasionally pressing the bread into the custard mixture. (Can be prepared 2 hours ahead. Cover and refrigerate.)
Preheat the oven to 350 degrees F. Bake until the pudding is set in the center, 45 to 50 minutes. Cool slightly. Serve warm.