In a shallow dish, mix the all-purpose flour with the kosher salt, black pepper, paprika, garlic powder, and cayenne pepper until evenly combined; set aside the seasoned dredge.
In a second dish, whisk the eggs and buttermilk until smooth.
Working one piece at a time, coat the cube steak in the seasoned dredge, dip in the egg–buttermilk, then coat again in the dredge, pressing so it adheres. Set breaded steaks on a rack and let rest 10 minutes to hydrate the coating.
Heat the neutral oil in a large heavy skillet (12-inch) over medium to medium-high heat to 350°F, with oil about 0.25 inch deep.
Fry the breaded steaks in batches without crowding until deep golden and crisp, 3–4 minutes per side; adjust heat to maintain sizzle. Transfer to a clean rack while you make the gravy.
Pour off all but about 3 tbsp fat from the skillet and return to medium heat. Whisk in 3 tbsp of the reserved seasoned dredge and cook 1–2 minutes until bubbly. Gradually whisk in the whole milk and simmer, whisking, until thick enough to coat a spoon, 4–6 minutes; taste and adjust seasoning if needed.
Return the steaks to the pan briefly to warm in the gravy or serve immediately on plates with the gravy spooned over the top.