In a small bowl, combine the paprika, oregano, garlic powder, onion powder, salt, black pepper, cayenne pepper, and dried thyme. Reserve 1 teaspoon of the seasoning mix. 

Sprinkle the remaining seasoning over both sides of the chicken breast. Drizzle them with about 1 tablespoon of olive oil and rub it in. Let the rubbed chicken breasts rest while you clean and slice the mushrooms. 

Heat 1 tablespoon of olive oil and melt 1 tablespoon of butter in a large skillet over medium heat. Add the chicken and cook until golden brown on both sides and cooked through, about 4-5 minutes on each side. Chicken is done when it reaches an internal temperature of 165 degrees. Plate the chicken and cover it to keep it warm. 

Melt 2 more tablespoons of butter in the skillet over medium-high heat. Add the mushrooms and cook until golden brown, stirring several times. Reduce the heat to low and add the remaining cajun seasoning and garlic. Cook for 1 minute while stirring continuously. Use a slotted spoon to plate the mushrooms and garlic. 

There should be about 2 tablespoons of fat in the pan. If not, add enough butter and melt it to make up the difference. Over medium heat, whisk in the flour, cooking for about 2 minutes while whisking constantly. Slowly whisk in the milk. Simmer over low heat until slightly thickened while scraping all the brown bits off the bottom of the pan. Season the sauce with salt and pepper to taste. 

Add the mushrooms, garlic, and chicken back to the skillet and simmer for a couple of minutes to warm. Sprinkle with fresh chopped parsley or thyme.