01 - Arrange three shallow bowls: one with the all-purpose flour, one with the eggs beaten together with the milk, and one combining the panko breadcrumbs, garlic powder, onion powder, paprika, salt, and black pepper.
02 - Pat the cleaned and trimmed mushrooms thoroughly dry using paper towels to ensure the breading adheres properly.
03 - Working in batches, dredge each mushroom in the flour, shaking off any excess to create a light, even coating.
04 - Dip each flour-coated mushroom into the egg and milk mixture, ensuring an even, thorough coating on all sides.
05 - Roll each mushroom in the seasoned panko breadcrumb mixture, pressing gently so the crumbs adhere firmly to the surface.
06 - Pour the vegetable oil into a deep fryer or a large, heavy-bottomed pot and heat to 350°F over medium-high heat.
07 - Carefully lower the breaded mushrooms into the hot oil in small batches and fry for 3 to 4 minutes, turning occasionally, until golden brown and crispy on all sides.
08 - Remove the fried mushrooms using a slotted spoon and transfer them to a plate lined with paper towels to drain excess oil.
09 - Sprinkle freshly chopped parsley over the mushrooms if desired and serve immediately while hot with your preferred dipping sauce.