Place a large piece of parchment paper on a cutting board. Pop open the biscuit container and pull apart the dough. Lay the pieces on the lined cutting board and set aside.
In a small bowl, using a fork, mix together the sugar and cinnamon, set aside.
In another small bowl, using a fork, whisk the egg yolk with a 1/2 teaspoon of water, set side.
Using a leaf shaped cookie cutter, punch out leaves. Using a pastry brush, brush the leaves liberally with the egg wash. Sprinkle on the cinnamon sugar.
Arrange the leaves close together in a circular pattern with the tips of the leaves facing out on a pizza pan lined with parchment paper. Place the wreath onto middle level of the oven for 17 minutes.
Meanwhile, in a large pot on medium heat, melt the butter. Using a rubber spatula, fold in the marshmallows, constantly stirring to avoid scorching. Once the mixture is melted, turn down the heat to low to keep it "pliable". Pour in the green food coloring. Combine until you see a rich and even green color throughout. Gently fold in the corn flakes.
Place a kitchen towel on a flat surface or counter, remove the wreath from the oven and place it on the towel. This will help you to prevent scorching your surfaces. Distribute the warm marshmallow mixture carefully over the wreath. Before the "holly" mixture cools completely, dot the wreath with cinnamon candies to look like holly berries.