Heat Conestoga® Reduced Sodium Classic Simple Split® Biscuits according to package directions. Combine oil, 1 teaspoon Italian seasoning, and 1⁄4 teaspoon garlic powder in a small bowl. Brush baked biscuits with margarine mixture.
Combine mayonnaise, yogurt, and remaining 1 tablespoon Italian seasoning and 1⁄2 teaspoon garlic powder; set aside.
Split biscuits and spread the insides with 1 tablespoon of yogurt mixture.
Layer spinach leaves, grilled chicken, and tomato slices on bottom half of biscuit. Top with top half of the biscuit.
Place on plate to serve.