Heat oil in a deep fryer or large pan on the stove until it reaches 325°F.
In a large bowl, whisk together flour, baking powder, baking soda, salt, pepper, and garlic powder until well combined.
In another bowl, whisk together buttermilk, egg, and hot sauce until smooth and cohesive.
Dredge each piece of chicken in the flour mixture, dip it into the egg mixture, then return it to the flour mixture again.
Fry each breaded chicken piece in hot oil for about 3-5 minutes until golden brown and cooked through.
To make gravy, add reserved oil to a pan, stir in reserved flour, then slowly add milk while whisking until thickened; season with salt and pepper.