Combine olive oil, salt, pepper, garlic powder, and oregano in a bowl. Place chicken breasts in bowl and let marinate for 30 minutes.
How to Season Chicken for Salad
Heat a grill to medium-high heat and brush with oil. Add chicken and cook about 5 minutes on each side. Remove to a cutting board.
In a large salad bowl or serving plate, add spinach and veggies.
What Goes on a Chicken Salad
Slice the chicken and toss with the salad.
Combine all dressing ingredients in a jar and stir together. Close lid and shake well.
Top salad with homemade Buttermilk Ranch Dressing.