Preheat the oven to 350°F (180°C / Gas Mark 4). Line cupcake pans with 24 cupcake liners and set them aside.
In a large bowl, using an electric standing or hand mixer, cream butter and sugar until fluffy. Beat in eggs one at a time, then mix in pumpkin purée.
In another bowl, whisk together or sift flour, baking powder, baking soda, pumpkin pie spice, cinnamon, ginger, and salt.
Add dry ingredients to wet in four additions, alternating with buttermilk until combined.
Use an ice cream scoop to divide the batter between the cupcake liners. Fill about ⅔ full.
Bake in the preheated oven for 20-25 minutes or until an inserted toothpick comes out clean.
Remove the cupcakes from the oven and let them cool in the pan for 5 minutes before transferring them to a wire rack to cool completely before decorating.
Make the Frosting
Using an electric stand or handheld mixer, beat the cream cheese and butter until fluffy. Gradually add powdered sugar and vanilla, and cinnamon (if using) until you reach a creamy, stiff-peak consistency.
Scoop out one-third of the frosting into a separate bowl and add leaf green gel food coloring. Remember, you can always add more coloring, but can't take it away! Stir in the food coloring until well combined and you reach the desired shade.
Transfer the green frosting to two piping bags. One with a round (#5) piping tip, and the other with a leaf (#352) piping tip.
Tint the other two-thirds of the frosting with orange gel food coloring to reach a pumpkin-orange color.
Make Pumpkin Tops
Place a 3D pumpkin silicone mold onto a baking sheet for stability. Pipe a little green frosting into the stem.
Spoon orange frosting into the cavities and level the tops. Place in the refrigerator for 10-15 minutes (or in the freezer for 5 minutes) to firm up.
Invert a cooled cupcake and press the domed side into a cavity. Give a gentle twist, then lift straight up to unmold the pumpkin-shaped frosting. Repeat for all cupcakes.
Decorate the tops of each pumpkin with additional stems (if it didn't quite come out of the mold), leaves, and vines. Serve and enjoy!
Notes
Tips
If the frosting sticks to the mold, chill longer or dust cavities lightly with powdered sugar.
If frosting slumps, stir in more powdered sugar for stiffness.
Substitutions
Swap cream cheese frosting with vanilla buttercream if preferred.
Leftovers
Store decorated cupcakes covered in the fridge for up to 3 days. Bring to room temperature before serving.
Freezing
Undecorated cupcakes freeze well for up to 3 months. Thaw overnight in the fridge and frost fresh.
Always consult the Food Standards Agency in your country for the most up-to-date advice on storing and freezing foods: Food Safety (USA) | Food Standards Agency (UK)