In a medium saucepan, bring 2 1/4 cups of water to a boil over high heat.
Stir in the grits and garlic powder. Reduce heat, cover, and simmer for 7 minutes until thickened, stirring occasionally.
Remove from heat and set aside.
In a small bowl, mix oregano, thyme, onion powder, and 1/8 tsp. salt. Sprinkle this blend over both sides of the chicken breasts, pressing gently to adhere.
Heat 1 tsp. oil in a large nonstick skillet over medium-high heat. Add the chicken and cook for 4 minutes.
Flip the chicken and cook for another 2-4 minutes until fully cooked through.
Spoon the grits onto a serving platter, sprinkle with the remaining 1/8 tsp. salt and shredded Cheddar. Place the chicken on top and cover to keep warm.
In the same skillet, heat 2 tsp. oil. Stir in squash, tomatoes, green onions, and 1/4 cup water. Cook for 4 minutes until the squash is golden on the edges.
Spread the sautéed vegetables over the chicken and grits or serve on the side.