Preheat oven to 350 degrees. Line a cupcake pan with yellow cupcake liners
In a large mixing bowl, add in the chocolate cake mix, water, vegetable oil, and eggs. Beat with a hand mixer on medium until incorporated.
Fill the cupcake liners ½ full with the cake batter.
Place into the oven and bake for 15 to 20 minutes until done. Insert a toothpick and if it comes out clean or with moist crumbs, the cupcakes are done.
Let the cupcakes cool completely. Work on making the Gryffindor Scarf cupcake toppers, and frosting while waiting
Frosting
In a large mixing bowl, add butter, powdered sugar, vanilla extract, and milk. Beat on medium until light and fluffy.
Using an offset spatula, frost each cooled cupcake.
Harry Potter Fondant Cupcake Toppers
Take 8 oz. of your white fondant and color with burgundy gel food coloring. Knead until completely tinted.
Color the remainder of your white fondant with the yellow food gel food coloring. Knead until completely tinted.
Sprinkle your work surface with cornstarch. Add cornstarch to a rolling pin as well. Roll both fondant colors separately until they are about a quarter of an inch thick.
Cut the burgundy fondant into strips, about 4 inches long and half an inch in width. Cut the yellow fondant into small rectangular pieces. You will need about 72 of them or 4 rectangles per a scarf.
Dab some water on the back of each yellow piece and place on the burgundy strip, spaced apart. You should be able to add about 4 pieces.
Cut some tassels on the end of each fondant scarf and place one on top of each cupcake.