Line an 8×8-inch square pan with parchment paper.

Combine the chocolate chips and sweetened condensed milk in a saucepan over low heat, stirring until smooth (about 5 minutes).

Pour the melted chocolate mixture into the prepared pan and spread it evenly.

Warm the raspberry jam in the microwave for 15-20 seconds until pourable.

Drizzle the warmed raspberry jam over the fudge and swirl with a knife.

Chill in the refrigerator for at least 2 hours until firm.

Lift the fudge out of the pan using the parchment overhang and cut into squares.