Preheat oven to 375°F. (use convection if your oven has this feature)
Line sheet pan with parchment paper.
Toss carrots, sweet potatoes and russet potatoes with half of the oil and a sprinkle of salt and pepper.
Place on sheet pan and put in the oven. Roast until about halfway done, roughly 20 minutes.
Toss remaining veggies with 1 tsp. oil, salt & pepper. Drizzle remaining oil over chicken breasts and season with salt & pepper.
Remove tray from oven and add chicken and the rest of your veggies. If using fresh herbs - tuck sprigs of thyme or rosemary between vegetables and lay on top of chicken. If using dried - sprinkle herbs over chicken with salt and pepper.
Return tray to oven for 25 - 28 minutes, or until chicken is done. If your chicken breasts are on the smaller side, start checking them at 24-25 minutes. If they are large, you may need the full 28 minutes.