Over low heat, stir constantly until the chocolate chips are melted and fully combined with the milk.
Pour the chocolate mixture into the lined baking pan. Use a rubber spatula to spread it out as evenly as you can.
Cover and refrigerate the pan for at least 2 hours to set.
Pull up the parchment paper to remove the fudge from the pan. Use a sharp knife to cut it into 4 equal pieces. Then cut each of those pieces into 9 so you end up with 36 pieces. Enjoy right away or refrigerate for later.
Notes
The mixture will be thick and may be difficult to spread in the pan. Shake it back and forth and use a rubber spatula to even it out as best you can.Store the fudge in an airtight container in the refrigerator for up to 2 weeks or in the freezer for up to 3 months.