Pat chicken dry and season both sides with salt, pepper, garlic powder, onion powder, and paprika. Heat 2 tablespoons of olive oil in a skillet over medium-high heat. Cook chicken for 5–6 minutes per side until golden brown and fully cooked (165°F). Remove and cover loosely with foil.
Add remaining olive oil to the same skillet. Sauté onions for 2–3 minutes, then add garlic and mushrooms. Cook until mushrooms are soft and browned. Sprinkle flour over vegetables and stir for 1 minute. Gradually whisk in chicken broth, then add cream, thyme, and Dijon. Simmer for 5 minutes, then stir in Parmesan. Season to taste.
Rinse rice until water runs clear. In a medium saucepan, bring water or broth to a boil with salt and butter. Add rice, reduce heat to low, cover, and simmer for 15–18 minutes until tender. Fluff with a fork.
Return chicken to skillet and spoon sauce over the top. Simmer 2–3 minutes to reheat and combine flavors. Serve over rice and garnish with parsley, Parmesan, and cracked black pepper.