Line an 8x8-inch baking pan with parchment paper, leaving edges overhanging for easier removal.

Combine white chocolate chips and sweetened condensed milk in a microwave-safe bowl. Heat in 30-second intervals, stirring until smooth.

Add vanilla extract and salt to the melted mixture and stir until well combined.

Spread the fudge mixture evenly in the prepared pan. Drop spoonfuls of warmed raspberry jam on top.

Using a butter knife, swirl the raspberry jam gently into the fudge without overmixing.

Cover the pan and refrigerate for at least 3 hours until firm.

Once chilled, cut the fudge into squares and serve.