Preheat oven to 180°C/350°F/Gas 4. Place 18 cupcake liners in cupcake pans and set them aside.
Using an electric handheld or standing mixer, beat the cake mix, eggs, butter, whole milk, and cinnamon until combined.
Use an ice cream scoop to fill the cupcake liners about three-quarters full.
Bake in the oven for 20 minutes or until an inserted toothpick comes out clean.
Meanwhile, to make the milk topping, whisk the cream, condensed milk, and evaporated milk together in a medium bowl until combined. Set it aside.
Remove the cupcakes from the oven, and leave them to cool for 5 minutes.
Use a bamboo skewer or a toothpick to poke holes randomly on the top of the cupcakes.
Spoon the milk mixture onto the top of each cupcake (about 2 tablespoons per cupcake).
Transfer the cupcakes to a wire rack to cool completely before decorating.
To toast the coconut, place the butter into a frying pan over medium heat and add the coconut. Stir to toast the coconut and ensure it doesn't burn.
Once the coconut has evenly lightly browned, remove and place onto a plate to allow to cool
completely before using.
To make the frosting, use an electric handheld or standing mixer to beat the butter, powdered sugar, cream, ground cinnamon, and vanilla until combined, smooth and holds a peak. This will take approximately 5-7 minutes.
Scoop the frosting into the piping bag fitted with an open star tip.
To make the cinnamon sugar, whisk the sugar and cinnamon in a small bowl, and set it aside.
Pipe a thick ring of frosting around the edge of the cupcake.
Coat the frosting in the toasted coconut.
Pipe a swirl of frosting on top of the toasted coconut layer.
Sprinkle with some of the cinnamon sugar and enjoy!