Set up a dredging station with two shallow bowls and a rack-lined sheet pan.
Whisk the dredging flour with baking powder, paprika, garlic, onion, cayenne, salt, and pepper.
Beat the eggs with buttermilk in the second bowl until smooth.
Pat cube steaks dry and season lightly with salt and pepper.
Dredge steaks in seasoned flour, dip in egg mixture, then coat again in flour.
Rest breaded steaks on the rack for 10 minutes to set the crust.
Heat the oil in a large skillet over medium-high until shimmering.
Fry steaks in batches, 3–4 minutes per side, until deeply golden. Drain on the rack.
Pour off all but 2 tablespoons drippings from the skillet; add the butter.
Whisk in the gravy flour and cook 1–2 minutes until lightly tan and nutty.
Gradually whisk in milk. Simmer, stirring, until thick and smooth, 3–5 minutes.
Season gravy with salt, plenty of black pepper, and hot sauce if using.
Serve steaks hot, smothered with the creamy pepper gravy.