In a bowl, combine the graham cracker crumbs, melted butter, sugar and pecans.
Press the mixture evenly into one 25-cm (10-in) round tart pan with a removable bottom, or two rectangular 10-cm X 25-cm ( 4-in X 10-in ) pans with removable bottoms. Bake in the centre of the oven for 15 minutes, or until the crust is lightly browned.
Meanwhile, steam (or boil) the potatoes until tender ( about 15 minutes ).
Mash the potatoes with a potato masher. Let cool. Using a spatula, stir in the maple syrup, eggs, sour cream and brandy. Pour the filling into the tart shell(s) and bake in the centre of the oven for 50 to 60 minutes, depending on the pan.
Remove tart from the oven and let cool for at least one hour before slicing. If desired, serve with maple-flavoured whipped cream.