Add the condensed milk to a microwave-safe bowl and microwave for 1 minute, or heat it in a saucepan over low heat until it just begins to simmer. Do not boil.
Sift the cocoa powder into the warm condensed milk in 3 batches, mixing well after each addition until smooth and thick.
Fold in the dried cranberries until evenly distributed throughout the mixture.
Transfer the mixture to a 6-inch square pan lined with cling film or parchment paper. Spread it evenly using a spatula.
Refrigerate for 2–3 hours, or until firm enough to cut.
Dust a chopping board and the top of the slab with cocoa powder. Turn the slab out, cut into squares using a hot knife, and coat each piece lightly in more cocoa powder before serving.
Recipe by Bake with Shivesh at https://bakewithshivesh.com/3-ingredient-cranberry-fudge/