Arrange the bread cubes on a baking pan and let sit uncovered overnight to dry.
Preheat the oven to 325 degrees. In a small bowl, soak the cherries in the Cognac for 20 minutes to soften.
Melt the chocolate in the top of a double boiler set over simmering water, stirring occasionally until smooth. Remove from over water. In a large bowl, stir the eggs, cream, sour cream, sugar, vanilla, and cinnamon until smooth. Whisk in the warm chocolate. Stir in the bread and the cherries with Cognac. Let stand until the bread fully absorbs the custard and no white from the bread is showing. Divide the mixture amoung six 10-oz. individual souffle dishes or one 2-qt. souffle dish. Bake the pudding until it is very firm and no longer jiggles, about 45 minutes. Remove from the oven and cool slightly.
In a small bowl, whisk the cream with sugar until soft peaks form. Put a large dollop beside each serving and garnish with a sprig of mint. Serve warm.