Preheat your oven to 180°C (350°F). Line a muffin tin with cupcake liners.
Boil the diced sweet potatoes until they are tender, then drain and mash them. Allow them to cool.
In a mixing bowl, sift together the flour, baking powder, ground cinnamon, and ground nutmeg. Set aside.
In another bowl, cream together the softened butter and caster sugar until light and fluffy.
Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
Gradually add the mashed sweet potatoes to the wet mixture and mix until well combined.
Alternately add the dry ingredients and the milk to the sweet potato mixture, beginning and ending with the dry ingredients. Mix until the batter is smooth.
Spoon the batter into the cupcake liners, filling each about two-thirds full.
Bake in the preheated oven for about 18-20 minutes or until a toothpick inserted into the centre of a cupcake comes out clean.
Remove the cupcakes from the oven and allow them to cool in the muffin tin for a few minutes before transferring them to a wire rack to cool completely.
In a separate bowl, whip the double cream, icing sugar, and vanilla extract together until it forms stiff peaks.
Once the cupcakes are completely cooled, pipe or spread the whipped cream topping on each cupcake.
You can optionally sprinkle a pinch of ground cinnamon or nutmeg on top for extra flavour.
