Cream margarine and sugar. Add the egg, vanilla and sour cream. Mix thoroughly.
Sift all of the dry ingredients into a large bowl. Gradually add to the margarine, sugar, sour cream mixture.
Scooping with a smallish ice cream scoop fill the cupcake cases about half full. Sprinkle the sugar, cinnamon, pumpkin pie spice and walnut mixture on top. Cover with another small scoop. Sprinkle again. Garnish with a lovely walnut half.
Pop them into the oven and bake for 30 minutes. Use the clean knife method to determine if done.