Cupcakes

1. Preheat the oven to 350°F and line a cupcake pan with paper liners.
2. Whisk the flour, baking powder, baking soda, salt and cinnamon in a mixing bowl. 
3. In another large bowl, beat the butter and sugar until smooth and fluffy. Add the eggs one by one, beating well after each addition. Add the milk and vanilla extract and beat to combine.
4. Sift the flour mixture into the bowl with the wet ingredients and gently fold everything together until just combined. Fold in the shredded apple.
5. Fill each liner 2/3 full with batter. Bake the cupcakes for 18 to 22 minutes or until a toothpick comes out clean. 
6. Leave the cupcakes in the pan for about 10 minutes before transferring them to a wire rack to cool completely.

Frosting

1. In a large mixing bowl, beat the butter and vanilla extract with an electric mixer until smooth and creamy.
2. Sift in the powdered sugar a little at a time, beating well after each addition.
3. If the frosting becomes too firm and difficult to mix, add milk 1 tablespoon at a time until the desired spreadable/pipeable consistency is reached.
4. Finally, add the cinnamon and beat again until well incorporated.

Assemble the Cupcakes

1. Once the cupcakes are completely cool, cut a hole into the center of each with a paring knife. The holes should go about ¾ of the way through each cupcake.
2. Fill each hole to the top with caramel sauce.
3. Spread or pipe swirls of frosting on top of each cupcake.
4. Drizzle a little extra caramel sauce over the top of each cupcake for decoration.