Begin by seasoning both sides of the chicken with kosher salt, freshly ground black pepper, and garlic powder. Next, prepare a breading station using three shallow bowls: in the first, combine the flour and cornstarch; in the second, whisk together the buttermilk, hot sauce, and egg; and in the third, add the Panko breadcrumbs.
Take each seasoned chicken piece and dredge it in the flour mixture first, shaking off any excess. Then dip it into the buttermilk mixture, allowing any extra liquid to drip off. Finally, coat the chicken thoroughly in the breadcrumbs, pressing them in gently to ensure a firm, even coating. Set the breaded chicken aside on a plate and repeat the process with the remaining chicken pieces.
In a large skillet, pour in a thin layer of vegetable or canola oil and heat over medium. Once the oil is hot, carefully add the breaded chicken cutlets to the pan, making sure not to overcrowd the skillet. You may need to cook them in 2 to 3 batches depending on the size of your pan, adding more oil as needed between batches. Fry the chicken for about 2–3 minutes per side, adjusting based on the thickness, until golden brown and the internal temperature reaches 165°F. Transfer the cooked cutlets to a paper towel–lined plate or board while you finish frying the rest.
In the meantime, whisk together the bang bang sauce in a small bowl and set aside. To assemble the sliders, cut the fried chicken cutlets into smaller portions to fit the slider buns. Place a piece of chicken on each bun, top with a slice of mozzarella cheese while the chicken is still warm, then drizzle generously with the bang bang sauce. Serve immediately and enjoy!