Preheat oven to 325 degrees F. Bring the Stout, cream, and 1/2 cup sugar, to a simmer in a medium saucepan, stirring until the sugar dissolves. Remove from the heat. Add 1 cup chocolate chips and whisk until melted and smooth. Set aside to cool. Whisk the eggs and vanilla in large bowl to blend. Gradually whisk in the cooled chocolate mixture. Add the bread cubes and the remaining chocolate chips to the custard, and toss to coat. Transfer to 1 1/2-quart-capacity shallow round, square or oval baking dish that you have greased with butter or oil. The batter will come close to the top of the pan. Sprinkle 2 tablespoons sugar over top. Bake until the custard thickens and the center is just set, about 50 to 60 minutes. Serve warm, cut a circle using a round biscuit cutter. Garnish with partially whipped whipping cream, lightly sweetened with sugar.