Preparation

Make the tart crust:

• Using a mixer fitted with a paddle attachment, mix the flour, sugar, orange zest, and salt in a large bowl on low speed for about 30 seconds. Add the butter and combine on low speed until the mixture looks crumbly, with pieces of butter about the size of dried peas, about 3 minutes. Add the egg and cream, mixing on low speed until the dough is just combined. If the dough is too dry to come together, add more cream, a tablespoon at a time. Gently mold the dough into a 1-inch-thick disk and wrap in plastic wrap. Refrigerate for at least 1 hour or for up to a week; the dough can also be frozen for up to a month.

Make the pumpkin filling:

• Spoon the pumpkin into a large bowl. Whisk in the eggs, one at a time, until thoroughly incorporated. Add both sugars and the flour, ginger, cinnamon, cloves, and salt. Whisk about 30 seconds. Whisk in the heavy cream and bourbon.

Make the streusel topping:

• Combine the flour, both sugars, cinnamon, and salt in a food processor fitted with a metal blade. Pulse briefly to mix. Add the butter and pulse until the butter has blended into the dry ingredients and the mixture is crumbly. Remove the blade and stir in the walnuts and crystallized ginger.

Assemble the tart:

• Position a rack in the center of the oven and heat the oven to 350°F. Take the tart dough from the refrigerator and let it warm up until pliable, 5 to 15 minutes. Unwrap the dough and set it on a lightly floured work surface. With as few passes of the rolling pin as possible, roll the disk into a 13-inch round, about 3/16 inch thick. Drape the round into a 11-inch fluted tart pan with a removable bottom gently fitting it into the contours of the pan. Fold the excess dough into the sides of the pan and press to create an edge that’s flush with the top of the pan and about 1/2 inch thick.
• Pour the pumpkin mixture into the unbaked tart crust. Scatter the streusel topping evenly over the pumpkin mixture.
• Bake until the topping is evenly cooked and no longer looks wet in the center, 50 to 65 minutes. Let the tart cool on a rack for at least 2 hours before serving (or wrap it in plastic and refrigerate overnight; before serving, let it sit at room temperature for 1 to 2 hours). Serve warm, at room temperature, or slightly chilled, with lightly sweetened whipped cream, if you like.