Position an oven rack in the center of the oven and preheat to 400 degrees F.
Cook the pancetta in a medium skillet over medium heat, stirring occasionally, until browned and crispy, 3 to 4 minutes. Remove to a paper towel-lined plate.
Roll out the round of dough slightly larger than a 9-inch tart pan and fit the dough into the pan. Put in the freezer while preparing the filling.
Whisk together the goat cheese, eggs, cream, curry powder, 1/2 teaspoon salt and the cayenne, if using, in a medium bowl (it's okay if there are lumps).
Remove the tart pan from the freezer. Use a fork to prick holes on the bottom of the crust.
Sprinkle the pancetta over the bottom of the crust. Pour the goat cheese custard over the top and spread in an even layer. Arrange the sweet potatoes on top. Drizzle with the oil and sprinkle with the cinnamon, and some salt and black pepper.
Bake until the filling is set and the sweet potatoes are cooked through, about 40 minutes.
Remove from the oven and let cool slightly before enjoying.