Heat oven to 350. Spray a 9 x 13" baking dish w/ cooking spray. In small bowl, combine chocolate chips, pecans and brown sugar. Mix well. In lg bowl, w/ mixer on medium, beat cake mix, butter and eggs for 2 min. Stir 1/2 the chocolate chip mix into batter. Spread batter into bottom of baking dish. Sprinkle remaining chocolate chip mix over batter. Bake 30 min. Cool. Cut into bars.