Preheat oven to 400°F (200°C) and line a large baking sheet with parchment paper or a silicone mat.
In a shallow bowl, whisk the egg whites until they are slightly frothy and aerated.
In a separate shallow dish, whisk together the grated Parmesan, whey protein isolate, oregano, thyme, garlic powder, paprika, salt, and pepper until uniform.
Dip each sweet potato medallion into the egg whites, allowing excess to drip off.
Press the medallion firmly into the Parmesan-protein mixture on both sides to ensure a thick coating.
Arrange the coated medallions on the baking sheet in a single layer with space between each piece.
Bake for 15 minutes, then carefully flip each medallion using a thin spatula.
Bake for an additional 12 to 15 minutes until the sweet potatoes are fork-tender and the protein crust is golden brown.
Remove from oven and let rest for 3 minutes to allow the crust to set before serving.