Step 1: In a shallow bowl, whisk together the flour, salt, pepper, garlic powder, onion powder, and cayenne pepper to create the seasoned dredging mixture.
Step 2: In a second shallow bowl, whisk together the buttermilk and egg until well combined.
Step 3: Pat the cube steaks dry with paper towels. Dredge each steak in the flour mixture, then dip into the buttermilk mixture, and finally dredge once more in the flour, pressing firmly to ensure a thick coating.
Step 4: Place the breaded steaks on a plate and let them rest for 10 minutes. This helps the breading stick during frying.
Step 5: Heat the oil in a large cast-iron skillet over medium-high heat until it reaches 350°F. Fry the steaks for 4-5 minutes per side until golden brown and cooked through.
Step 6: Remove the steaks to a wire rack to drain. Carefully pour off all but 3 tablespoons of the oil from the skillet, keeping the browned bits.
Step 7: To make the gravy, whisk 3 tablespoons of the seasoned flour into the remaining oil in the skillet. Cook for 1-2 minutes to brown the flour slightly.
Step 8: Gradually whisk in the milk, stirring constantly to prevent lumps. Simmer until the gravy thickens, then season with extra black pepper and salt to taste. Pour over the steaks and serve immediately.