Preheat oven to 400°F.
Lay the eggplant slices on a rack or colander and generously sprinkle both sides of the eggplant with salt. Allow the eggplant to sweat for about 30 minutes. This process will help draw out the moisture from the eggplant which will result in a crispier crust.
After 30 minutes, rinse the eggplant under running water to remove the excess salt. Then pat the eggplant dry with a towel.
In a wide bowl, combine the panko, flour, oregano and black pepper. In a separate bowl, whisk the eggs together.
Coat both sides of each eggplant with the egg. Then dip the eggplant into the panko mixture. Gently press the panko into the eggplant with your hands so that the panko adheres well on both sides. Top each eggplant with a 1/2 tbsp of butter.
Coat a baking sheet with the olive oil. Transfer the eggplant onto the baking sheet. Bake in the oven for about 30 minutes, flipping the eggplant once half way through to brown both sides.