Begin by beating softened unsalted butter in a large mixing bowl for about 2 minutes until fluffy and pale.

Gradually mix in sweetened condensed milk until fully combined and smooth.

In a separate bowl, sift together all-purpose flour, cocoa powder, and a pinch of salt.

Gently fold the dry ingredients into the butter mixture until just combined.

Cover the bowl with plastic wrap and refrigerate the dough for 30 minutes.

Roll the chilled dough between two sheets of parchment paper to about 1 cm thickness.

Preheat your oven to 320°F and arrange cut cookies on a lined baking sheet, leaving space between them.

Bake for 5-8 minutes until edges feel firm and centers may remain slightly soft.

Allow the cookies to cool on the baking sheet for about 2-3 minutes before transferring to wire racks.