In a large mixing bowl, combine buttermilk, salt, black pepper, garlic powder, and paprika. Whisk until well mixed.

Add the chicken pieces to the marinade, ensuring they are fully submerged. Cover and refrigerate for at least 1 hour, or up to overnight. This step tenderizes the chicken and infuses it with flavor.

In a separate large bowl, combine flour, panko breadcrumbs, salt, black pepper, onion powder, and dried oregano. Mix well to ensure even distribution of the seasonings.

Set up a breading station: remove the marinated chicken from the fridge, and let excess marinade drip off before dredging in the flour mixture. This helps the breading adhere better.

Take each piece of marinated chicken and coat it in the flour mixture, pressing lightly to ensure an even coating. Shake off any excess flour and place on a plate. Repeat until all chicken pieces are breaded.

In a deep frying pan or Dutch oven, heat vegetable oil over medium-high heat until it reaches 350°F (175°C). Use a thermometer to check the temperature for accurate frying.

Carefully add breaded chicken pieces to the hot oil in batches, ensuring not to overcrowd the pan. Fry for about 4-5 minutes on each side, or until golden brown and cooked through (internal temperature should reach 165°F or 74°C).

Use a slotted spoon to remove the chicken from the oil and place on a plate lined with paper towels to absorb excess oil.

Serve the popcorn chicken hot with your favorite dipping sauces, such as ranch, honey mustard, or barbecue sauce.