Preheat your oven to 425°F (220°C). Line a baking sheet with foil or parchment for easy cleanup. Do you need a reason? No. Do it anyway.
Be a brave warrior and pound the chicken to even thickness (about 1/2 inch). This helps it cook evenly and avoid rubbery surprises. Season both sides with salt, pepper, garlic powder, and oregano.
Set up your dredging station: whisk eggs in one bowl, and mix breadcrumbs with 1/4 cup parmesan and a pinch more salt in another. Dip each chicken piece in eggs, then coat with the breadcrumb mix.
Drizzle a little olive oil on the baking sheet, then place the breaded chicken. Bake 12–15 minutes until lightly golden and almost cooked through.
Remove from oven. Spoon marinara over each piece, then top with mozzarella and a sprinkle of additional parmesan. Return to the oven and bake 6–10 minutes more, until cheese is melted and bubbly.
Turn on the broiler for 1–2 minutes if you want an extra-snazzy golden crust. Watch closely to avoid a cheese volcano.
Garnish with fresh basil if you’ve got it. Let rest a couple minutes, then slice and serve. Easy enough for weeknights, classy enough for guests.