Prepare an 8x8 baking dish with parchment paper, leaving a 1 inch overhang for easy removal. Spray with nonstick cooking spray and set aside.
In a microwave-safe bowl, combine 1 bag of white chocolate chips and 3/4 cup of sweetened condensed milk. Heat in 30 second intervals, stirring frequently, until melted. Add a few drops of yellow food coloring and stir to mix through.
Pour the yellow fudge mixture into the prepared pan. Chill in the fridge for 10-15 minutes or until set.
In medium bowl, add 8 ounces (2/3 bag) of white chocolate chips and 1/2 cup condensed milk. Microwave to melt. Add a few drops of orange food coloring. Pour the orange mixture over the yellow layer and carefully spread out. Chill in the refrigerator to set.
When the fudge is set, melt the remaining chips with 1/4 cup sweetened condensed milk. Stir until smooth and pour the white mixture over the orange layer. Chill until full set. Remove and cut into squares.
Notes
Use gel food coloring for the best color without thinning the mixture.
Let each layer chill fully before adding the next - this is the only way to get clean defined layers.
Don't add water to thin the mixture if it seizes. Use heavy cream instead.
Wipe the knife between every single cut. The sugar sticks immediately.
Cut into triangles instead of squares if you want them to look more like actual candy corn.
Line the pan with parchment paper before you start - trying to remove the fudge without it is a disaster.
If you can't find orange food coloring, or it doesn't come in your variety pack, mix red food color with yellow.