Lightly grease slow cooker with nonstick cooking spray. Add 1/4 cup water.
In a small bowl, whisk together olive oil and all spices (everything but Ranch dressing). Rub mixture all over chicken then place chicken in the bottom of your slow cooker. Cook on high for 2-4 hours or on low for 6-7 hours or until chicken is tender enough to shred.
Remove chicken to a cutting board, and let rest 5 minutes before shredding. Drain excess liquid in slow cooker. Return shredded chicken and add 1/4 cup ranch dressing (or more for “saucier” chicken. Stir to combine.
Serve in tacos, in burritos, on salad, etc.
*If you aren't sure how much to add, then start with 1/4 teaspoon then add more to taste at the end of cooking.