Line 9-inch square pan with foil, with ends of foil extending over sides. Spray pan with cooking spray and rub with a paper towel. Set aside. Also spray a small thin-bladed knife with cooking spray (a butter knife works well for this). Set aside.
Combine sugar, butter and half and half in a sauce pan (at least 3 quart-size) over medium heat until mixture comes to a full rolling boil, stirring constantly (don't mistake bubbling at the edges for a full boil). Cook for exactly 4 minutes, stirring constantly. Remove from heat.
Add white chocolate chips, cover and allow to sit for 2 minutes, then stir until all chocolate is melted and mixture is smooth. Add marshmallow creme and candy corn oil extract. Stir again until smooth and well mixed.
Pour approximately half of mixture into prepared pan. tilt to cover bottom, if needed. Sprinkle 6-8 drops of orange food coloring randomly over the surface of the fudge. Repeat with the yellow food coloring. Quickly pour the other half of the fudge mixture over the first layer. Again, sprinkle 6-8 drops each of orange and yellow food coloring randomly over the surface of the fudge.
Using the side of the prepared knife, run it back and forth through fudge, creating a swirled pattern. As you run the knife through the fudge, pull some up from the bottom to to created the swirled effect all the way through the fudge. Once you get a pretty swirly pattern stop. If you swirl too much the whole mixture will turn orange. Cool completely. Use foil handles to lift fudge from pan before cutting into squares.