Start by preheating your oven to 400°F and lining a baking sheet with parchment paper. Place your chicken breasts between two sheets of plastic wrap and gently pound them to about half an inch thick. This keeps the chicken tender and helps it cook at the same speed as the crust browns.
Add the pecans, breadcrumbs, garlic powder, smoked paprika, oregano, salt, and pepper to a food processor. Pulse a few times until you get a fine, even crumb you don't want big chunks, or the coating won't stick well. Pour the mixture into a shallow bowl once it's ready.
In one bowl, add the flour. In a second bowl, whisk together the eggs and milk. In the third bowl, add your pecan crumb mixture. Season the chicken with a pinch of salt and pepper before you start dredging, since this is your only chance to season the meat directly.
Dip each chicken breast into the flour first, shaking off the excess. Then dunk it into the egg wash, letting any extra drip away. Finally, press it firmly into the pecan crumbs so the coating sticks on every side. I always press a little extra at the edges, since that's where crumbs tend to fall off.
Arrange the breaded chicken on your prepared baking sheet, leaving space between each piece. Drizzle or brush the tops lightly with olive oil or melted butter this helps the crust turn a deep golden brown in the oven instead of staying pale. Bake for 20-25 minutes, flipping halfway through if you like extra crispness on both sides.
Use a meat thermometer to check the thickest part of the chicken; it should read 165°F. Let the chicken rest for a few minutes before slicing or serving, since this keeps the juices locked inside instead of running out onto the plate.