In food processor or blender, finely chop pecans. Add bread crumbs and Cajun seasoning; pulse to combine.
Transfer to a shallow dish. Place buttermilk in second shallow dish. Dip chicken in buttermilk; coat with breading.
In large skillet, heat oil over medium heat. Add chicken; cook until browned and internal temperature reaches 170°F, turning occasionally (about 10-12 minutes).