Preheat your oven to 325°F and line a cupcake pan with cupcake liners.

In a bowl or stand mixer, combine the vegetable oil, eggs, and water with the chocolate cake mix. Mix until just combined.

Using a ¼ cup measuring cup, scoop the batter into the cupcake liners filling each about ⅔ full.

Bake the cupcake pan for 15 minutes or until a toothpick inserted into the center comes out clean.

Let the cupcakes cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.

Beat the softened butter on medium-high speed until light and fluffy.

Gradually add powdered sugar 1 cup at a time and heavy cream 1 tablespoon at a time, alternating between the two until fully incorporated.

Mix in vanilla extract and a pinch of salt. Stir in green gel food coloring until desired shade is achieved.

Using a piping bag fitted with a 1M tip, pipe the green frosting in circular motions to resemble a tree shape.

Decorate with star sprinkles and Christmas pearls while the frosting is still soft.