Season 2 ribeye or sirloin steaks (or your preferred cut) with salt, pepper, and garlic powder to taste. Heat a grill or skillet over medium-high heat and coat with olive oil or cooking spray. Cook the steaks for about 4-5 minutes on each side, or until they reach your desired level of doneness. Remove from heat and let them rest.
To air fry the steak, preheat the air fryer to 400 degrees F, preheat for 3-5 minutes. Place the steaks in the preheated air fryer basket and cook for about 7-10 minutes for medium-rare, or adjust the time according to your desired level of doneness, flipping halfway through.
Heat 1 tablespoon of olive oil in a skillet over medium heat. Add 1/2 cup diced mushrooms, 1/4 cup finely chopped onions, and 2 cloves minced garlic to the skillet. Sauté until the vegetables are tender.
Pour in 1/2 cup heavy cream and 1/4 cup chicken or beef broth, then sprinkle in 1/4 cup grated Parmesan cheese, 1 tablespoon Cajun seasoning, 1/2 teaspoon paprika, and 1/4 teaspoon cayenne pepper (adjust to taste). Stir to combine. Simmer the sauce for a few minutes until it thickens slightly. If using, stir in 1/2 cup cooked chopped shrimp (optional).
Place the cooked steaks on serving plates. Spoon the Toowoomba-style sauce over the steaks, covering them generously. Serve the Toowoomba Steak hot, accompanied by your favorite sides like mashed potatoes and steamed vegetables.