Chicken-Fried Mushrooms & Gravy

Ingredients: For the Mushrooms: 1 pound mushrooms (such as oyster, portobello, or shiitake), cleaned and sliced thickly 1 cup buttermilk (or plant-based milk with 1 tablespoon lemon juice) 1 cup all-purpose flour 1/2 cup cornstarch 1 teaspoon garlic powder 1 teaspoon onion powder 1 teaspoon smoked paprika 1/2 teaspoon salt 1/2 teaspoon black pepper