Heat chocolate chips and chocolate-hazelnut spread together in a large pot over low heat until melted, about 5 minutes. Add 1/2 of the cereal to the chocolate mixture and stir until coated. Transfer the coated cereal to a large resealable bag and add 1/2 of the confectioners' sugar; seal bag and shake until cereal is coated. Transfer puppy chow to an airtight container. Repeat with remaining chocolate mixture, cereal, and confectioners' sugar.
