01 - Whisk buttermilk with hot sauce in a large bowl. Add mushrooms and toss to coat thoroughly. Let marinate for 15 minutes to absorb flavors.
02 - Combine flour, cornstarch, garlic powder, onion powder, smoked paprika, cayenne pepper, salt, and black pepper in a shallow dish. Mix well to distribute spices evenly.
03 - Remove mushrooms from buttermilk, allowing excess liquid to drip off. Press each mushroom into the flour mixture to coat thoroughly. For extra crunch, return dredged mushrooms to buttermilk and repeat the flour coating process.
04 - Heat vegetable oil in a deep skillet or pot to 350°F. Fry mushrooms in batches for 4–5 minutes, turning occasionally, until golden brown and crispy. Transfer to a paper towel–lined plate to drain excess oil.
05 - Melt butter in a saucepan over medium heat. Whisk in flour and cook for 1–2 minutes until lightly golden and fragrant. Gradually whisk in milk, then add black pepper, salt, and garlic powder. Cook, whisking constantly, for 3–5 minutes until thickened and smooth.
06 - Arrange crispy fried mushrooms on a serving platter. Pour warm gravy generously over the top or serve alongside for dipping. Best enjoyed immediately while hot and crispy.