Prepare the sides. Have the mashed potatoes prepared and keep them covered and warm. If serving asparagus, trim and prepare it for sautéing. If serving spaghetti, bring a large pot of salted water to a boil.
Set up the breading station. Lay a long sheet of aluminum foil across your work surface. On one end, combine the flour, garlic powder, onion powder, salt, and pepper. On the opposite end, combine the Italian panko and Parmesan. Place the eggs in a shallow bowl between the two mixtures and whisk vigorously.
Bread the chicken. Dredge each chicken cutlet on both sides in the seasoned flour, shaking away the excess. Dip into the beaten eggs and allow excess egg to drip off. Transfer to the Parmesan-panko mixture and press the coating firmly onto both sides.
Fry the chicken. Add 1/2 inch oil into a large skillet and over medium heat. Working in batches, fry the cutlets for approximately 3–4 minutes per side. Cook until deeply golden, crisp, and reaches 165°F internally. Transfer to a wire rack.
Prepare your chosen side. For asparagus, sauté in a little olive oil over medium-high heat with salt and pepper for approximately 4–6 minutes, until crisp-tender. For the viral variation, cook the thin spaghetti according to package instructions until tender, then drain.
Make the sauce. Add the lemon juice, chicken stock or white wine, sliced scallions and 2 tablespoons heavy cream to a small saucepan over medium-low heat. Bring to a gentle simmer and cook for about 3 minutes to reduce slightly.
Emulsify the butter. Reduce heat to low. Whisk in the remaining 3 tablespoons heavy cream. Remove from heat and add the cold cubed butter, whisking constantly until sauce is smooth, creamy, and glossy. Season with salt and pepper to taste.
Sauce the spaghetti, if using. Toss the drained spaghetti with a few generous spoonfuls of the warm lemon butter sauce.
Assemble. Spoon a little sauce onto the bottom of each plate. Add mashed potatoes and either sautéed asparagus or lemon-butter spaghetti. Add a crispy chicken cutlet and generously spoon the warm sauce over the chicken and sides.
Garnish and serve. Use a vegetable peeler to remove thin strips of lemon peel, avoiding as much white pith as possible, then slice into very thin strips. Garnish the chicken with lemon peel and minced parsley and serve immediately.