Preheat the oven to 200°F.

Set up a dredging station. In a shallow dish, stir together the all-purpose flour, seasoned salt, garlic powder, black pepper, paprika, and cayenne (if using). In a second shallow dish, whisk together the eggs and whole milk.

In a large skillet, heat the canola oil and unsalted butter over medium heat until bubbling. Working in an assembly line, dip the cube steaks into the flour mixture, then into the egg mixture, and then dredge again in the flour. Transfer to a sheet pan. Repeat until all the steaks are coated with the breading. Line a separate sheet pan with foil.

Add 3 steaks to the hot skillet and cook until they begin to brown on the edges, 3 to 5 minutes on each side. Remove them to the foil-lined sheet pan, season with 1/2 teaspoon of kosher salt while hot, and tent loosely with foil. Repeat with the remaining 3 steaks and remaining 1/2 teaspoon salt. Place the steaks in the oven to keep warm.

Reduce the heat under the skillet to medium-low and add the all-purpose flour. Cook, whisking constantly, until the roux is bubbling and lightly colored, 1 to 2 minutes. Whisk the whole milk into the roux, 1 cup at a time, and stir in the kosher salt and freshly cracked black peppercorns. Cook, whisking constantly, until the gravy thickens, about 5 minutes.

Serve the chicken-fried steaks with the hot black peppercorn gravy on top.