Line 2 large cookie sheets with a silicon mat, or parchment paper, and set aside.
In a large, 8 quart, stock pot on medium-low heat melt the 1 cup unsalted butter and large marshmallows. This will take 6 to 8 minutes and you will need to stir constantly to keep the mixture from burning.
Once the butter and marshmallows are completely melted and stirred together, turn off the heat, and add the vanilla extract and green liquid food coloring. Stir to evenly incorporate.
Using a large rubber spatula, gently stir in the cornflakes until they are completely coated with the melted marshmallow mixture.
Lightly spray a ½ cup dry measuring cup, or ½ cup cookie scoop, with cooking oil and scoop out a leveled amount of the coated cornflakes. Flip the mixture out onto the prepared cookie sheet, leaving 2 inches between each one. Repeat until you have placed all the wreath cookies onto the cookie sheets. I got 6 wreath cookies per cookie sheet.
With the remaining 1 tablespoon of butter, generously coat your fingertips with the butter. Using your butter-coated fingertips, create a hole in the center of each wreath cookie about 1 inch in size. You will want to form your wreaths rather quickly before the marshmallow mixture starts to firm up.
Once your Christmas wreaths are formed, place 4 cinnamon imperial candies onto each of your Christmas wreath cookies. *You can decorate your cookies however you please so you may need more than the 48 candies that the recipe calls for.*
Allow the Christmas wreath cookies to firm up on the cookie sheets for 1 hour in the refrigerator. Once your cookies have firmed up you can carefully place them onto a platter and serve.