Chocolate Marble Terrine

Butter a 1 1/2-quart terrine mold or loaf pan and line with plastic wrap.

For the Dark Chocolate Mousse, cut chocolate and butter into small pieces and combine in a bowl.

In a medium saucepan, bring about 2 inches of water to a simmer.

Remove pan from heat.

Set the bowl of chocolate over the hot water and stir until chocolate has melted.

Cool, and then add the cream, 2 tablespoons at a time, stirring well.

Stir in the cognac.

Cover mixture with plastic and let stand at room temperature until firm and cool, at least 2 hours.

Do not refrigerate.

For the White Chocolate Mousse, follow the procedure above, substituting white chocolate for the semisweet.

For the Chocolate Sauce, cut chocolate into small pieces.

In a saucepan, combine sugar, corn syrup, and 1 cup water, and bring to a boil.

Remove from heat and stir in chocolate.

Let chocolate mixture stand 2 minutes, and then whisk until smooth.

Set aside to cool.

Recipe can be prepared to this point a day ahead.

For the meringue, in a medium saucepan, bring about 2 inches of water to a simmer.

Combine egg whites and sugar in the bowl of an electric mixer or in a large bowl.

Set bowl over the simmering water and gently whisk until egg whites are warm and sugar is dissolved, about 3 minutes.

Remove bowl from simmering water, and using the whisk attachment of mixer, whip until meringue is cool and stiff peaks form, about 7 minutes.

Set aside.

Beat White Chocolate Mousse on medium speed until lightened in texture and color, about 3 minutes.

Repeat with Dark Chocolate Mousse.

Immediately fold 1/3 of the meringue into the Dark Chocolate Mousse; 2/3 of the meringue into the White Chocolate Mousse.

Spoon the Dark Chocolate Mousse on top of the White Chocolate Mousse in one bowl.

Using a spatula, marbleize the mixtures with about 6 turns of the spatula, being careful not to overmix.

Gently pour mixture into the mold.

Give mold several raps against a towel-covered surface to level the mousse, and then cover with plastic wrap.

Refrigerate for 8 hours or up to 2 days.

Just before serving: Wrap the mold in a hot, wet cloth.

Invert pan onto a cutting board and cut into 1-inch-thick slices with warm, dry knife.

Spoon Chocolate Sauce onto dessert plates and gently lay slices on top.