Add 2 cups (240 g) powdered sugar, 1 12‑ounce (340.2 ml) can evaporated milk, ½ cup (113.5 g) salted butter (cut into pieces), and ¾ cup (135 g) semisweet chocolate chips to a medium saucepan.

Stir or whisk over low heat just until the sugar is moistened and the butter begins to melt (about 1–2 minutes) so the ingredients start to combine and the chocolate softens.

Increase heat to medium and stir constantly with a heatproof spatula or whisk. Bring the mixture to a gentle boil (small bubbles around the edges), watching closely to prevent it from boiling over.

Once it reaches a gentle boil, maintain that gentle boil and continue stirring constantly for 8 minutes, adjusting the heat as needed to avoid scorching or rapid foaming.

Remove the saucepan from the heat and stir briefly until smooth. Let the sauce cool slightly (about 5–10 minutes) before serving; it will thicken as it cools.

Store any leftovers in an airtight container in the refrigerator for up to 1 month. Reheat gently as needed (for example, over low heat in a saucepan or in short intervals in the microwave), stirring until smooth.