2 cups graham cracker crumbs (about 16 crackers)
6 tablespoons unsalted butter, melted
1 tablespoon granulated sugar
2 tablespoons packed light-brown sugar
1/2 teaspoon coarse salt
1/2 teaspoon ground cinnamon
1/4 teaspoon ground ginger
3 ounces bittersweet chocolate (preferably 61 percent cacao), finely chopped
6 ounces semisweet chocolate (preferably 55 percent cacao), chopped
4 tablespoons unsalted butter, cut into small pieces
1 can (15 ounce) solid-pack pumpkin
1 can (12 ounce) evaporated milk
3/4 cup packed light-brown sugar
3 large eggs
1 tablespoon cornstarch
1 teaspoon pure vanilla extract
1 1/2 teaspoons coarse salt
3/4 teaspoon ground cinnamon
3/4 teaspoon ground ginger
1/4 teaspoon ground nutmeg
1/8 teaspoon ground cloves
1 ounce milk chocolate, melted
whipped cream, optional