Mix seasoned flour ingredients and place them on a plate. Dredge the steaks.
Heat a large skillet over medium-high heat. Add the oil. Brown the cube steaks and place them in the bottom of a 5-7 quart slow cooker.
Deglaze the pan with the 1/2 cup water. Pour this over the cube steaks in the slow cooker.
Place the mushrooms on top of the steaks.
Mix the ranch seasoning (link to homemade in ingredient list) with the melted butter and pour over the mushrooms. Sprinkle Parmesan cheese on top.
Cover and cook on low 4-7 hours, high 3-5 hours. Check for doneness at the minimum time--all cookers cook differently and Ninja will cook in 2/3 of regular slow-cooker time.