Trim any excess fat from the chicken breasts. Place each breast between two sheets of plastic wrap or parchment paper. Using a meat mallet or rolling pin, gently pound the chicken until it’s about 1/4 inch thick.
Season both sides of the chicken breasts generously with salt, pepper, garlic powder, and onion powder.
Set up three shallow bowls or plates: place the flour in the first, whisk the eggs in the second, and spread the breadcrumbs in the third.
Dredge each chicken breast first in the flour, shaking off any excess. Then dip it into the beaten eggs until fully coated. Finally, press it firmly into the breadcrumbs, making sure every surface is covered. Set aside on a plate.
Pour vegetable oil into a large skillet until it’s about 1/4 inch deep and heat over medium-high heat until shimmering but not smoking. Carefully add the breaded chicken breasts and fry for 3-4 minutes per side or until golden brown and cooked through. Adjust heat as needed.
Transfer the cooked schnitzel to a paper towel-lined plate to drain excess oil. Let rest for a few minutes to lock in moisture.
While the schnitzel rests, whisk together the mayonnaise, freshly minced garlic, lemon juice, and chopped parsley in a small bowl. Taste and adjust seasoning with salt and extra lemon juice if desired.
Plate your schnitzel alongside a dollop of lemon aioli. Serve with sides like roasted potatoes, steamed veggies, or a crisp salad.