In a large, heavy saucepan, melt chocolates and butter over low heat, stirring until melted.
In a large mixing bowl, beat together eggs, whipping cream, sugar, vanilla, and cinnamon until just combined. Gradually add cream mixture to melted chocolate, stirring constantly. Fold in bread. Pour into a greased 8x8x2-inch baking dish.
Bake in a 325 degree F oven for about 1-1/4 hours or until a knife inserted near the center comes out clean. Cool slightly. Serve with whipped cream or ice cream, if you like. Makes 12 servings.