Prepare an 8x8 pan with parchment paper. Set aside.
In a medium-sized pot, heat the sweetened condensed milk and chocolate chips over low heat. Stir constantly.
Once the chocolate chips are completely melted (this will probably take around 5 minutes), remove from heat and stir in the pecans and marshmallows.
Pour into your prepared pan. Refrigerate until the fudge is firm. Keep the fudge refrigerated until ready to serve.
