Heat oven to 300°F. In medium bowl, mix melted butter and brown sugar. In ungreased 15x10x1-inch pan, place corn puffs snacks and pecans. Pour butter mixture over snacks mixture, stirring to coat evenly.
Bake 20 to 25 minutes, stirring twice, until golden brown.
Remove 6 cups snacks mixture; place on waxed paper. Sprinkle chocolate chips over remaining hot mixture in pan; toss until chocolate is melted and pieces are completely coated. Cool each mixture completely, about 10 minutes.
When mixtures are completely cooled, toss together in large bowl or container.