Preheat your oven to 400°F.
Season the chicken breast with salt and pepper.
In a shallow bowl, beat the egg. In another bowl, place the crushed pecans.
Dip the chicken breast first in the egg, then coat evenly with the crushed pecans.
Place the coated chicken on a lightly greased baking sheet.
Peel and cube the sweet potato into 1-inch chunks, toss with a drizzle of olive oil, salt, and pepper, and spread on a separate baking sheet.
Trim the green beans and toss them lightly with olive oil, salt, and pepper. Place them on the same baking sheet as the sweet potato or on a separate one if space allows.
Roast the chicken, sweet potato, and green beans in the oven. The chicken should bake for about 20-25 minutes until fully cooked and pecan-crusted. The vegetables may take about 25-30 minutes, stirring halfway through for even roasting.
Once cooked, serve the crispy pecan-crusted chicken alongside the roasted sweet potato and green beans.