Giant Frosted Donut Cake

["Mix batter according to package or recipe directions.", "Divide batter equally into two donut bundt pans.", "Bake for the suggested amount of time (found on the box of cake mix).", "Remove cakes from oven and allow to completely cool, about 2 hours.", "Remove cooled cakes from pans and place them flat side down on a parchment paper covered plate.", "Transfer cakes to freezer and allow to harden, about 1 hour and up to two days.", "When the cakes are hard, remove them from the freezer and turn them upside down on a level surface (cutting board or plate).", "Use a sharp knife to level the flat side of the cakes off a bit.", "Taking the melon baller, scoop out a ring around the middle of each cake.", "Spoon about half of your frosting into a piping bag fitted with a large round tip, #2A or bigger.", "Fill the scooped out portion of the cakes with this frosting.", "Place one cake on top of the other, flat sides together to form a giant donut cake.", "Frost the top of the donut with the remaining frosting.", "Place sixlet ""sprinkles"" randomly over the top of the cake."]