Line an 8×8 inch pan with parchment paper, leaving some overhang on the sides.

In a microwave-safe bowl, combine the white chocolate chips and sweetened condensed milk. Microwave in 30-second intervals, stirring well after each, until the mixture is completely smooth and fully melted, about 1.5 to 2 minutes total.

Add the vanilla extract and a pinch of salt into the melted chocolate mixture. Stir until all ingredients are fully incorporated and smooth.

Pour the combined fudge mixture into the prepared pan, spreading it out evenly and smoothing the top with a spatula.

Drop small spoonfuls of the warmed seedless raspberry jam evenly spaced over the top of the fudge mixture.

Using a butter knife or the tip of a spatula, gently swirl the raspberry jam into the fudge to create a marbled effect, being careful not to over-swirl.

Place the pan in the refrigerator and chill the fudge for at least 3 hours, or until firm. Once set, use the parchment paper overhang to lift the fudge from the pan. Cut into 36 small squares and serve.