Preheat oven to 425°F.
In a bowl, mix the ground chicken with salt, garlic powder, and onion powder until just combined.
On parchment, press into a very thin rectangle large enough to match your bun layout.
Lightly dust with flour, brush with egg, then coat fully in panko, pressing gently to adhere.
Spray generously with avocado oil until fully coated. Flip and repeat on the other side.
Transfer to a sheet pan and bake for 18–22 minutes, then broil for a few minutes until golden and crispy.