In a food processor, combine the flour, pecans, icing sugar and salt. Add the butter and pulse until the butter is the size of peas. Add the water and pulse until the dough just begins to hold together. Add water if necessary. Remove the dough from the food processor and shape by hand into a disc.
On a floured surface, roll the dough into a disc large enough to line a 23-cm (9-inch) pie plate. Line the pie plate and refrigerate for 30 minutes.
With the rack in the middle position, preheat the oven to 190°C (375°F).
In a food processor, purée the sweet potato, sugar and spices until smooth. Add the eggs and cream and process until smooth.
Scrape the filling into the pie shell and bake until the filling is barely set, about 35 minutes.
Let cool. Refrigerate until chilled.
With the rack in the middle position, preheat the broiler.
Top the pie with a tightly packed layer of marshmallows. Brown under the broiler, 1 or 2 minutes. Watch the pie closely, as marshmallows start to burn quickly. To serve, cut the pie with a damp blade.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.