In a large bowl of a stand mixer, place the butter, sugar, egg, and vanilla, and blend until well mixed.
In a separate bowl, add the flour, baking powder, baking soda, corn starch, and white chocolate chips, and mix well.
Add the dry ingredients into the mixing bowl with the wet ingredients, and blend until well mixed.
Add the sprinkles, M&M's, and Oreos, and mix well.
Grease and flour a Wilton Cookie Pan and line the bottom with parchment paper.
Pour the cookie dough into the pan, and smooth out the dough evenly in the pan.
Bake at 350 for about 15 minutes, or until golden brown.
Remove from oven and place pan on a wire rack to cool - DO NOT REMOVE COOKIE FROM PAN!
When the cookie is cool, place the frosting in a pastry bag, with the small star tip, and pipe frosting all around the edge of the cookie.
Add Sprinkles on top of the frosting.
Cut into 3-inch pieces, and place on dessert plates.
Add a scoop of Vanilla Ice Cream to the top of each piece, and drizzle with the Hot Fudge Topping.
Add more sprinkles, M&M's and any extra candy on top of the Ice Cream.
Serve, and Enjoy!