Preheat oven to 356°F (180°C) and line a muffin baking pan with 12 cupcake liners.
In a medium sized bowl, whisk together the eggs, sugar, oil, and vanilla extract.
Stir in milk, then add the rest of the ingredients (flour, cocoa powder, baking powder, salt), and mix until just combined but do not over mix. They batter won't be very thick, sort of runny and that's okay.
Pour the batter into liners, and bake for 18-20 minutes or until the toothpick comes out clean. When completely chilled, make the frosting by adding 1/2 teaspoon of food colouring to the vanilla frosting and beat with an electric mixer until colour is evenly distributed. If you want a brighter green colour add more food colouring.
To decorate the cupcakes with green frosting, place it into a piping bag attaching tip #27 and create tree shapes. Finally, decorate with funfetti, sprinkles, or sugar pearls.