large star piping tip #825; pastry bag or resealable plastic bag; 1-ounce ice cream scoop or a tablespoon; fondant strip cutter (or ruler); fondant rolling pin or wooden rolling pin; snowflake cookie cutter; 18-inch or 20-inch round cake board or platter
For the marble cupcakes: Preheat the oven to 350 degrees F. Line 2 cupcake pans with white liners.
Evenly separate the vanilla cake batter into 3 bowls. Dye one bowl Christmas red, one bowl green and one bowl white. Using a 1-ounce ice cream scoop or tablespoon, put one scoop of each color into the lined cupcake pans, filling two-thirds of the way. Swirl the colors together with a wooden skewer or the back of a spoon. Bake until a toothpick inserted in the center comes out clean, 18 to 20 minutes. Allow to cool completely before assembling the wreath.
For the decorations: While the cupcakes are baking and cooling, dye your buttercream frosting a Christmas green and put it into a pastry bag with a large star tip at the end.
For the snowflakes: Dust a clean surface with cornstarch. Roll the white fondant out so it is 1/8-to-1/4-inch thick. Use your snowflake cookie cutter to cut out snowflake shapes.
For the fondant bow and streamers: Dust a clean surface with cornstarch. Roll the red fondant out so it is 1/4-inch thick. Cut one strip that is approximately 2 inches wide and 10 inches long and one that is 1-inch wide and 5 inches long. Fold the 10-inch-long strip in half to find the center. Add a little bit of water as glue to the center of the strip and fold each end into the middle. Pinch the center together. Take the shorter strip and wrap it over the center (securing with a little bit of water) and close on the backside of the bow.
Roll the leftover red fondant out so it is 1/4-inch thick and cut 2 strips – each should be 2-by-5 inches. Cut the top of each strip into a triangle and cut the bottom of each strip so that it resembles ribbon tails.
To assemble: Once the cupcakes have cooled completely, assemble them into a wreath shape on whatever board or platter you plan to use for service. Make sure to leave a blank circle in the center. Once you like the placement, attach each cupcake to the board with a dot of buttercream.
Pipe a large buttercream rosette on top of each cupcake with the green buttercream, making sure to fill in all the gaps. Add your fondant bow, snowflakes and assorted holiday sprinkles to complete your wreath.