Whisk butter milk well with salt and pepper powder . In a bowl add chicken and pour buttermilk, mix well. Cover and marinate it in fridge for 2+ hours or overnight(8 -10 hours) Then remove from fridge and drain off excess buttermilk.
Place all purpose flour on a bowl or plate. Add all spice powders to the flour and mix well everything. Set aside.
Crack open a egg into a separate bowl , add salt and pepper, whisk well and set aside.
In a wide bowl mix panko bread crumbs, oregano, paprika, pepper powder, and mix well. Salt is not added here as panko bread crumbs already contains salt in it.
Preheat Oven to 200 deg Celsius. Alternatively if you deep frying , In a wide pan heat oil for deep frying.
Add chicken bites into spice flour and coat it with flour, then dip it in egg and then coat with panko bread crumb mix. Repeat this to all the chicken pieces.
Line a baking tray and brush with oil. Arrange chicken pieces on a baking tray , spray oil or drizzle some oil on top of the arranged chicken pieces .
Put inside a oven and bake for around 18 minutes. Around half the way after 10 minutes of baking , open tray from the oven. Turn the chicken pieces to other side, drizzle some oil on top. Put it back in oven and continue to bake for 6 to 8 minutes.
Once done , garnish with some fresh herbs, sprinkle some kosher salt and serve hot with favourite sauce or dips of your choice.