In a bowl, combine the chicken, buttermilk, and ¼ of the hot sauce. Toss well to coat.
Preheat the oven to 425°F and line a baking sheet with parchment paper.
Combine the corn flakes crumbs, cheese cracker crumbs (if using), ⅗ of the fajita seasoning, and black pepper in a medium-size bowl. Stir to combine.
Remove each piece of chicken from the buttermilk, and dredge through the crumbs, pressing gently to adhere. Place on the prepared baking sheet. Make sure not to crowd your pan; if necessary, use two baking sheets. Lightly brush/drizzle the chicken with olive oil.
Bake for 15-20 minutes or until the chicken is cooked through.
Meanwhile, make the black pepper sauce by stirring together the melted butter, the rest of the hot sauce, remaining fajita seasoning, and a pinch of black pepper.
Serve the chicken with the black pepper sauce alongside the Greek yogurt ranch for dipping. Enjoy with tater tots, with ketchup and additional herbs if desired, and cucumber water.