Mexican Chocolate Cake

INGREDIENTS

• 5 ounces fine-quality bittersweet chocolate (not unsweetened), finely chopped
• 2 large eggs
• 1/2 cup confectioners sugar
• 2 cups chopped pecans (71/2 ounces)
• 1/4 teaspoon salt
• 2 tablespoons vanilla
• 3/4 cup water
• 2 sticks (1 cup) unsalted butter
• 1/2 cup half-and-half
• 1 teaspoon baking soda
• 1/2 cup Dutch-process unsweetened cocoa powder
• 2 cups granulated sugar
• 1/2 cup well-shaken buttermilk
• 1/2 stick (1/4 cup) unsalted butter
• 1/2 teaspoon cinnamon
• 2 cups all-purpose flour