Prepare the pan: Line an 8×8-inch square baking dish with parchment paper or lightly grease it to prevent sticking.
- Melt the fudge base: In a saucepan over medium heat, combine the white chocolate chips, sweetened condensed milk, and butter. Stir constantly until the mixture is completely smooth and the white chocolate is fully melted.
- Add flavor: Remove the saucepan from the heat and stir in the vanilla extract and a pinch of salt to enhance the flavor.
- Swirl in the caramel: Pour the white chocolate fudge mixture into the prepared baking dish. Then, drizzle the caramel sauce over the top of the fudge and gently swirl it into the mixture using a knife or skewer. Be careful not to over-mix; you want to create beautiful ribbons of caramel throughout the fudge.
- Set the fudge: Place the dish in the refrigerator and let the fudge chill for at least 2-3 hours, or until it is fully set and firm.
- Serve: Once the fudge has set, remove it from the pan using the parchment paper and cut it into small squares. Serve and enjoy!