For the cinnamon cupcakes:

1. Preheat the oven to 180°C (160°C Fan). Line a 12-hole muffin tin with 10 cupcake liners
2. In a medium bowl, mix together the flour, baking powder and cinnamon
3. In a large mixing bowl, beat the butter for 3-4 minutes until creamy
4. Add in the brown sugar and beat until light and fluffy
5. Add the eggs one at a time, mixing well after each egg. Mix in the vanilla extract
6. Fold in the flour mixture, being careful not to overmix
7. Add the milk and mix until just combined
8. Scoop the batter into the cupcake liners, filling each liner 3/4 full (or with 75g of batter)
9. Bake for 18-20 minutes, until a skewer inserted in the centre comes out clean
10. Remove from the oven and allow to cool in the tray for 5 minutes. Move the cupcakes to a cooling rack to cool completely.

For the caramel sauce:

1. Place the unwrapped toffees and double cream into a saucepan
2. Heat on very low heat until the toffees have melted and the mixture is smooth. 
3. Remove from the heat, and leave to cool to room temperature

For the caramel frosting:

1. In a large mixing bowl, cream the butter for 5 minutes, until pale and fluffy
2. Slowly mix in all the icing sugar, until combined and smooth
3. Pour in 1/2 the cooled caramel sauce and beat into the frosting

To assemble the cupcakes:

1. Spoon the frosting into a piping bag, with a piping tip of your choice
2. Swirl the frosting onto the cupcakes
3. Spoon over the caramel sauce