Preheat the oven to 180°C (350°F).
Prepare a baking tray by lining it with parchment paper.
In a deep bowl, mix the sweet potato cubes, lemon slices, green beans, olive oil, rosemary, thyme, garlic, salt, and black pepper until the sweet potato is well coated.
Season the chicken breasts with salt, black pepper, and paprika, then place them on the tray over the sweet potato mixture.
Place the tray in the oven for about 25 minutes, or until the vegetables and chicken are fully cooked.
Serve the roasted chicken and sweet potato hot from the oven.