In a microwave-safe bowl, combine 1 cup of semi-sweet chocolate chips. Heat in the microwave in 20-second intervals, stirring after each, until fully melted and smooth, about 1 minute total.

Once melted, pour in one 14 oz can of sweetened condensed milk. Stir well until combined and glossy.

Cover the bowl with plastic wrap and chill in the refrigerator for at least 30 minutes.

Finely chop 1/4 cup of walnut pieces and set aside in a shallow dish.

Once chilled, scoop out about a tablespoon of the mixture and roll into a ball. Repeat with remaining mixture.

Roll each chocolate ball in the finely chopped walnuts until well-coated.

Store the coated truffles in an airtight container at room temperature for 3-4 days or refrigerated for up to 2 weeks.