Preheat oven to 350°F. In a medium bowl, stir graham cracker crumbs, sugar and oil until evenly moistened (mixture will be dry). Press in bottom and up sides of a 9-inch pie plate. Bake until golden brown and crisp, 12 to 15 minutes. Let cool completely on a wire rack.
In a large bowl, whisk pumpkin, coconut milk, eggs, brown sugar, salt and spices. Pour into crust and smooth the top. Bake until set, except in center, and crust is brown, 45 to 60 minutes. Let cool completely on a wire rack. Slice; top with a small dollop of whipped cream (about 1 Tbsp.), if desired.