Preheat oven to 350°F and line a baking sheet with parchment paper.
Place frozen phyllo shells on the baking sheet.
Combine the pumpkin, maple syrup, egg, milk, vanilla and pumpkin pie spice in a bowl. Whisk until combined and smooth.
Spoon the filling into each phyllo shell right up to the top.
Bake for 15-20 minutes until the filling is just set. Check halfway through and if the filling has sunk down while cooking, spoon in any leftover pumpkin pie mixture on top.
Remove from the oven and let rest at least 15 minutes to cool before topping and serving.
FOR THE WALNUT TOPPING:
Combine all the ingredients in a small sauce pot and bring to a boil.
Once boiling, turn off the heat and pour into a small bowl. Place the bowl in the refrigerator to chill.
Once chilled and nut mixture has thickened, spoon on top of the pumpkin pie bites before serving.
Notes
Any leftover pumpkin pie filling can be poured into a ramekin and baked alongside the pumpkin pie bites.