Chocolate Cranberry Bread Pudding

1 loaf (16 ounces) challah or brioche8 tablespoons (1 stick) melted unsalted butter2 cups fresh or dried cranberries1 2/3 cups milk1 cup heavy creamScant cup sugar14 ounces bittersweet or semisweet chocolate, chopped (see note)7 eggs1 teaspoon vanilla extractLightly sweetened whipped cream or creme fraiche (optional)Position the rack in the lower third of the oven. Heat the oven to 350 degrees.Tear the loaf into large shreds, about 2-by- 3/4-inches. To do this, pinch a piece of the bread at the top of the loaf and start pulling. If the loaf is sliced, tear the slices. Spread the shreds on a large baking sheet and bake until lightly toasted, about 5 minutes. Remove from the oven and immediately drizzle melted butter over the bread. Toss lightly to distribute the butter. Cover the bottom of the pan or pans with half of the bread. Sprinkle all the cranberries over this bread. Top with the remaining bread. Set aside.In a heavy saucepan, heat the milk, cream and sugar to a simmer. Off heat, add the chocolate and stir until melted and smooth. In a medium bowl, whisk the eggs and vanilla. Add the chocolate mixture to the eggs and stir until well blended. Pour the mixture over the bread, making sure the top layer of bread is completely moistened. Cover the pan loosely with a piece of foil.Bake for 15 minutes. Remove the foil and bake 15 minutes more, or until the pudding bubbles vigorously around the edges although the center is still very liquid if the pan is jiggled. Remove the pudding from the oven (it will continue to thicken) and cool on a rack. Serve warm, at room temperature, or cold, plain or with a dab of whipped cream or creme fraiche.Serves 12 to 14.Cook's note: You can use any domestic bittersweet or semisweet chocolate without a percentage on the label, or any boutique or imported brand marked 50 percent to 62 percent. Or, substitute 10 ounces chocolate marked 66 percent to 72 percent and increase sugar by 2 tablespoons. "Chocolate Holidays: Unforgettable Desserts for Every Season" by Alice Medrich(2005 Artisan, $21.95)