Prepare the Pan:

Line an 8x8-inch baking dish with parchment paper, allowing a bit of overhang for easy removal. Lightly grease the paper with non-stick spray or butter.

Melt the Fudge Base:

In a medium saucepan over low heat, combine the white chocolate chips, sweetened condensed milk, and a pinch of salt. Stir constantly until the mixture is fully melted and smooth. Be careful not to overheat.

Add Vanilla:

Remove the saucepan from heat and stir in the vanilla extract until well combined.

Create the Strawberry Swirl:

In a small bowl, warm the strawberry jam slightly in the microwave (about 10–15 seconds) until pourable. If desired, add food coloring to the jam for a vibrant swirl effect.

Assemble the Fudge:

Pour the white chocolate mixture into the prepared baking dish and spread evenly. Drop spoonfuls of strawberry jam on top of the fudge in several spots. Use a knife or skewer to gently swirl the jam into the fudge, creating a marbled pattern.

Chill to Set:

Refrigerate the fudge for at least 3 hours, or until firm.

Cut and Serve:

Once set, lift the fudge out of the pan using the parchment paper. Cut into small squares with a sharp knife. Store in an airtight container in the refrigerator for up to 1 week.