Chocolate Bread Pudding with Orange Custard Sauce

For sauce:
1 1/2 cups low-fat milk
1 2-by-1-inch strip orange zest, preferably organic
1 large egg
1/4 cup sugar
2 teaspoons all-purpose flour
1 1/2 tablespoons Grand Marnier, (optional)

For bread pudding:

1 tablespoon canola oil
2 teaspoons butter
8 1-inch slices whole-wheat sandwich bread, crusts removed, cut in half on the diagonal
1/3 cup unsweetened cocoa powder
Pinch of salt
2 1/2 cups low-fat milk
2 ounces good-quality bittersweet (not unsweetened) chocolate, chopped
2 large eggs
1/2 cup packed light brown sugar
1 teaspoon vanilla extract

Make Orange-Scented Custard Sauce and refrigerate:

Combine milk and orange zest in a small heavy saucepan. Bring almost to a simmer over low heat. Remove pan from heat, cover and let stand for 30 minutes.

Whisk egg, sugar and flour in a bowl until smooth.

Rewarm milk over low heat until steaming. Gradually add milk to the egg mixture, whisking constantly. Return mixture to saucepan.

Cook sauce over low heat, stirring constantly, until thick enough to coat the back of a spoon, 7 to 8 minutes. (Do not allow sauce to come to a simmer.) Remove from heat.

Pour sauce through a fine-meshed sieve into a bowl. Discard orange zest. Stir in Grand Marnier, if using. Place plastic wrap directly on the surface of the sauce and refrigerate until cold, about 2 hours.

Preheat oven to 400?F.

Heat oil and butter over low heat in a small saucepan just until butter melts. Brush both sides of the bread slices with butter mixture and place on a baking sheet. Bake until golden brown, 5 to 7 minutes per side.

Overlap toasted bread slices in an ungreased 9-inch square baking dish. Reduce oven temperature to 325?.
Whisk cocoa and salt in a medium saucepan. Gradually whisk in milk. Bring to a bare simmer over low heat. Remove from heat, add chocolate and whisk until it melts.

Whisk eggs, brown sugar and vanilla in a medium bowl until blended. Gradually whisk hot chocolate mixture into egg mixture. Pour custard over bread in baking dish. Let stand for 15 minutes. Meanwhile, boil water for the water bath.

Set baking dish in a roasting pan and place in the oven. Add boiling water to the roasting pan to reach halfway up sides of baking dish. Bake pudding until just set, 20 to 25 minutes. (It should still jiggle slightly in the center.) Remove baking dish from roasting pan and cool on a wire rack for about 20 minutes. Serve warm with Orange-Scented Custard Sauce.