Preheat your oven to 400°F.
Peel and cube the sweet potato, then toss with 1 teaspoon olive oil, a pinch of salt, and pepper. Spread evenly on a baking sheet.
Roast the sweet potato cubes in the oven for about 25-30 minutes until tender. Once cooled slightly, blend or mash until smooth to form a creamy mash.
While the sweet potato is roasting, pound the chicken breast slightly to even thickness.
In a small bowl, combine the egg white, chopped mixed herbs, minced garlic, salt, and pepper.
Brush the herb-egg white mixture evenly over both sides of the chicken breast.
Heat a non-stick skillet over medium-high heat and sear the chicken for 2-3 minutes on each side until a light crust forms.
Transfer the chicken to the oven (or continue in the skillet with a lid on low heat) and cook for an additional 10-12 minutes until fully cooked.
Plate a serving of roasted sweet potato mash alongside the herb-crusted chicken. Serve warm and enjoy.