Set rack in the middle of the oven, and preheat oven to 375 degrees F (190 degrees C). Lightly oil a 9 inch pie plate. Set aside.
Step 2
Spread nuts over a baking pan. Toast for 7 to 10 minutes, or until the smell of nuts fills the kitchen. Set aside 16 pecan halves for garnish.
Step 3
Combine oats, flour, remaining pecans, 1/2 teaspoon cinnamon, and a pinch of salt in a food processor bowl. Pulse until mixture becomes a coarse meal. Transfer to a mixing bowl. Whisk together oil and 3 tablespoons maple syrup, and mix into dry ingredients to form a soft dough. Press mixture into prepared pie plate. Crimp edges. Bake for 10 minutes, and set aside to cool.
Step 4
Blend soymilk and arrowroot in the food processor until the arrowroot is completely dissolved and the mixture is smooth, about 15 seconds. Add pumpkin, 1/2 cup maple syrup, ginger, 1 1/2 teaspoons cinnamon, 1/2 teaspoon salt, nutmeg, and cloves; process until thoroughly blended. Pour filling into baked crust, and smooth the top with a spatula.
Step 5
Bake for about 35 minutes, or until the crust is lightly browned and the outside inch of the filling is set. Don't worry if the center is still soft; it firms up as the pie cools. Transfer pie to a wire the rack. Gently press toasted pecan halves into hot filling in 2 concentric circles. Cool to room temperature, and then chill until set, about 3 hours. Serve chilled or at room temperature.
