1 cup all-purpose flour, plus more for dusting
1/4 cup plus 1 tablespoons granulated sugar
1/4 cup unsweetened cocoa powder
1/2 teaspoon salt
1/2 teaspoon ground cinnamon
1/4 teaspoon ground cloves
1/2 cup (1 stick, 8 tablespoons) cold unsalted butter, cut into small pieces
1 large egg
4 ounces semisweet chocolate, finely chopped

For the filling:
1 can (15 ounces) unsweetened pumpkin puree
3/4 cup packed light brown sugar
1 cup sour cream
3 large eggs
1 teaspoon ground cinnamon
1 teaspoon ground ginger
1/4 teaspoon freshly grated nutmeg
1/4 teaspoon salt
1/8 teaspoon ground cloves

For the topping:
2 ounces semisweet chocolate, finely chopped