Preheat the oven to 400 degrees. Mix together 1/2 teaspoon of salt, 1/2 teaspoon of ground pepper, and 1/2 teaspoon of garlic powder. Sprinkle over the chicken breasts. Place the chicken breasts on a sheet pan coated with cooking spray. Bake for 25 - 30 minutes or until completely cooked and internal temperature reads 165 degrees. After the chicken is cooed set aside to cool and then cut into pieces.
Make the salad dressing. In a small container, wisk together the olive oil, white wine vinegar, grated garlic cloves, 1/4 teaspoon of salt, and oregano.
To layer the salads start with adding 2 tablespoons of dressing into the bottom of each 32-ounce mason jar. Store unused dressing in the refrigerator. Then add the tomatoes, cucumbers, olive, feta, chicken, and top with the romaine lettuce. Tighlty place the lid on and refrigerate up to 5 days.
When you're ready to eat dump the salad ingredients into a medium to large bowl and enjoy.