Line an 8x8 pan with parchment paper, leaving overhang on two sides. Be sure your bowls and spatula are completely dry (a drop of water can cause chocolate to seize).
Add chopped white chocolate or wafers, condensed milk, butter, and salt to a double boiler (or in a heat-proof bowl set over a saucepan with water) and bring water in the bottom of boiler to a simmer. Stir gently until mixture is just melted and smooth. Remove from heat and stir in vanilla and butter extracts. If you prefer to use microwave: heat at 50% power in 30-second bursts, stirring between each, until fully melted and combined.
Scoop out about 1 cup of the melted chocolate into a small bowl and add a few drops of yellow food coloring. Stir to combine and continue adding drops until shade is vibrant. Spread mixture into an even layer in the prepared pan. Freeze 5-7 minutes, just until the top firms up.
If the remaining melted white chocolate stiffens while you work, warm it gently for 10-15 seconds to loosen it back up. Scoop out another 1 cup of chocolate, tint it orange, and spread it over the yellow layer. Freeze 5-7 minutes.
Spread the remaining white chocolate (keep it white) over the orange layer and immediately press the candy corn evenly over the top while the surface is still soft.
Refrigerate fudge for at least 2 hours, until firm. Lift out by the parchment paper, place on cutting board, and cut into squares with a warm, dry knife, wiping the blade between cuts.