To make the skull toppers, line a cookie sheet or tray with parchment paper or a non-stick baking mat and set it aside.
When using fondant, use cornstarch as you would flour when making dough. Dust your work surface, hands, and tools.
Knead the silver fondant in your hands to make it soft and pliable. Dust the mold with cornstarch using a clean, dry paintbrush.
To make a skull, pinch off about 2 tablespoons of fondant and press it into the mold cavity.
Leave for 3 minutes before carefully removing it from the mold. Set the skull on the prepared cookie sheet to dry in a cool, dry place (not the fridge) overnight or for 24 hours if possible.
Repeat to make 18 skulls total. TIP! Always make extra fondant decorations as backup!
To make the cupcakes, preheat the oven to 350°F/180°C/Gas 4. Line cupcake pans with 18 cupcake liners and set them aside.
Using an electric standing or hand mixer, beat the cake mix, eggs, milk, and butter until combined and smooth.
Use an ice cream scoop to divide the batter between the cupcake liners. Fill about ¾ full.
Bake in the preheated oven for 20 minutes or until an inserted toothpick comes out clean.
Remove the cupcakes from the oven and leave to cool in the pan for 5 minutes before transferring to a wire rack to cool completely before decorating.
To make the frosting, use an electric stand or handheld mixer and add the butter, powdered sugar, cream, and vanilla to the bowl.
Beat on medium speed until creamy, smooth, and stiff peaks form.
Scoop 1½ cups of frosting into a separate bowl and add a few drops of neon pink food coloring. Remember, you can always add more coloring, but not remove it! Stir in the food coloring until well combined and you reach the desired shade. Cover and set aside.
Add several drops of black food coloring to the remaining frosting. Stir in the food coloring until well combined and you reach the desired shade of black.
Use a medium cookie scoop to place mounds of black frosting onto each cupcake.
Flip each cupcake upside down and press down lightly onto a piece of parchment paper to flatten the frosting into a thick disk.
Pour all the sprinkles into a bowl and stir to combine.
Dip each frosted cupcake into the sprinkles to cover. Set them aside.
Place a large star tip into a large piping bag. Add the pink frosting down one side of the piping bag and the black frosting down the other side. Gently squeeze to begin piping out the frosting so it mixes together.
Pipe a swirl of pink-black frosting on the top of each cupcake.
Place a fondant skull on top of each frosted cupcake. Enjoy, and Happy Halloween!