For the sauce, heat 1 Tbsp olive oil in a medium saucepan over medium-high heat.
Add in onions and saute for 2 minutes then add garlic, and saute 30 seconds longer.
Stir in crushed tomatoes, 1/4 tsp salt, oregano, and 2 fresh basil sprigs, then season with salt and pepper to taste.
Bring mixture to a simmer then reduce heat to low and allow to simmer 20 minutes, stirring occasionally, until thickened. Remove basil, remove from heat and cover saucepan with lid.
For the chicken, while sauce is simmering, sprinkle each side of the chicken cutlet lightly with salt, let stand at room temperature 10 minutes.
In a shallow dish, whisk together flour and egg until smooth. In a separate shallow dish, toss together Parmesan cheese, Panko bread crumbs, garlic powder, oregano and 1/4 tsp pepper.
Pat chicken dry with paper towels then working with 1 chicken cutlet at a time, dredge chicken in egg mixture coating both sides and allowing excess to run off, then immediately transfer to Parmesan mixture and coat both sides with mixture, while pressing to allow crumbs to adhere.
Transfer chicken to a plate and repeat process with remaining chicken cutlets. Pour olive oil into a 10-inch non-stick skillet and heat over medium-high heat.
Once oil is shimmering, add 2 coated chicken cutlets and fry without moving them until bottom is crispy and golden brown, about 2 - 3 minutes, then using metal tongs rotate to opposite side and cook until golden brown, about 2 - 3 minutes longer until (chicken should be about 155 degrees, it will cook just briefly in oven).
Toss Mozzarella and provolone together and sprinkle cheese mixture in a mound over cutlets.
Broil in oven until cheese is melted (you can let it brown a little if you like) about 1 - 2 minutes (keep a close eye on it!).
Remove from oven and cover each cutlet with 2 Tbsp marinara sauce. Sprinkle tops evenly with remaining 1/4 cup fresh basil and serve immediately (serve extra sauce with pasta on the side).
Recipe Source: adapted with some changes from Cook's Illustrated
*This is two large stems (sorry there was a mix-up with the video, it's not two leaves).