Line a 9×9-inch baking dish with parchment paper or aluminum foil, ensuring the surface is fully covered. Set aside.

In a large saucepan set over medium-low heat, combine the candy corn and peanut butter. Cook for 2–3 minutes, stirring frequently. If the mixture does not begin melting, add the sweetened condensed milk earlier than directed to prevent scorching.

Once the candy corn begins to soften, add the sweetened condensed milk. Continue cooking, stirring constantly, until the mixture becomes smooth and fully melted.

Bring the mixture to a gentle simmer, then add the white chocolate chips. Stir continuously until fully melted and smooth. If using salt, stir it in at this stage.

Remove the saucepan from the heat. Carefully pour the mixture into the prepared baking dish, smoothing the surface into an even layer with a spatula.

Allow the fudge to cool at room temperature for approximately 15 minutes. Transfer to the refrigerator and chill until fully set.

If desired, melt 1 cup semi-sweet chocolate chips with 1 teaspoon vegetable oil in the microwave in 20-second increments, stirring after each interval until smooth. Allow the chocolate to cool slightly, then transfer it to a resealable plastic bag. Snip a small section from one corner and pipe the chocolate over the chilled fudge. Return to the refrigerator to set.

Once firm, cut the fudge into squares and serve. Store remaining portions in an airtight container.