Pound chicken breasts to an even 1/2-inch thickness using a meat mallet. This ensures even cooking throughout.

In a wide, shallow dish, whisk together egg whites, cornstarch, and juice from half the lemon until well combined.

In another dish, combine breadcrumbs, Parmesan cheese, parsley, kosher salt, black pepper, and lemon zest.

Dip each chicken breast first in the egg mixture, then thoroughly coat in the breadcrumb mixture, patting gently to help it adhere.

Place the coated chicken on a wire rack and let rest for 20-30 minutes to help the coating set.

Preheat oven to 450°F.

Heat olive oil in a large oven-proof skillet over medium-high heat. Add chicken and cook for about 3 minutes until golden brown on one side.

Carefully flip the chicken and transfer the skillet to the preheated oven. Bake for approximately 8 minutes until chicken is cooked through (internal temperature of 165°F).

While chicken bakes, prepare the sauce. In a separate pan, melt 1 tablespoon of butter and sauté the shallots until soft and translucent.

Add white wine, heavy cream, chicken broth, and remaining lemon juice. Simmer until reduced by half, about 8-10 minutes.

Reduce heat to low and whisk in the remaining 4 tablespoons of cold butter, one tablespoon at a time, until sauce is smooth and velvety.

Stir in minced sage and season with salt, white pepper, and cayenne to taste.

Serve the chicken with the sauce either pooled beneath or drizzled over the top.