Without shaking or tilting the can, carefully open chilled coconut milk. Remove solidified cream from top, reserving liquid, and place in a bowl. Add powdered sugar and 1 teaspoon vanilla, and beat with an electric mixer until medium peaks form, about 3 minutes. Chill until ready to use. Whisk together remaining coconut milk liquid, unsweetened coconut milk, granulated sugar, and cocoa in a medium saucepan. Bring to a simmer over medium, stirring constantly. Cook, stirring constantly, until sugar is dissolved and mixture is hot, about 10 minutes. Remove from heat, and whisk in bittersweet chocolate, 3/4 teaspoon cinnamon, salt, and 2 teaspoons vanilla. Pour into 4 serving cups, and top with whipped coconut cream, a sprinkle of ground cinnamon, toasted coconut, and shaved chocolate.