1In large bowl, mix cereal, pecans and marshmallows. Spread mixture on 2 large ungreased cookie sheets.
2In 2-cup microwavable measuring cup, microwave chocolate chips and oil uncovered on High 1 minute, stirring after 30 seconds. If necessary, microwave 15 to 30 seconds longer or until smooth. Drizzle chocolate over cereal mixture.
3Refrigerate until set; about 10 minutes. Break into pieces. Store in airtight container.