Preheat oven to 350°F. Place cupcake liners in a 12-cup muffin pan. Set aside.
Prepare cake mix according to package instructions with the above substitutions (buttery spread instead of butter/apple sauce and baking powder instead of eggs). Don't forget the water.
Use a muffin scoop or ice cream scoop to divide batter into the 12 cupcakes. Bake according to package (I baked mine for 22 minutes). Let cool.
Meanwhile make the frosting. Place shortening in a large bowl and mix on medium with an electric mixer for 3 minutes. Turn mixer to low, then gradually add the sugar, milk and vanilla. Once all is combined, turn mixer up to medium and beat for 3 minutes. Divide frosting into 3 bowls. You only need a small amount for the leaves, so most of the frosting can be in 2 bowls. Color the smaller amount green and the other 2 bowls your colors of choice. Place green frosting in pastry bag fitted with a #352 tip. Set aside. Place a large piece of plastic wrap on the counter. Spread some of one color onto it, the spread some of another color on top. Roll up the icing and twist the ends of plastic. Cut about ½" off one side of the plastic roll. Place that into a pastry bag fitted with the 7-petal Russian pastry tip. Spread a little bit of icing onto each cupcake, then pipe roses. Pipe leaves next. Serve immediately or store in the refrigerator for up to 4 days. Let them come to room temperature before eating.
Notes
Use your favorite cake mix for this recipe. It doesn't have to be gluten free.*Note: the package called for 3 eggs, so I substituted the applesauce and baking powder for the eggs. If you want to use eggs, just omit the apple sauce and baking powder.