Preheat your oven to 400°F.
In a small bowl, combine lemon juice, chopped rosemary, chopped thyme, a minced garlic clove, olive oil, salt, and pepper.
Place the chicken breast in a baking dish and coat evenly with the lemon herb mixture. Let it marinate for at least 15 minutes.
Prepare the mashed potatoes by boiling the medium potato (cut into chunks) until tender. Drain and mash with butter, milk, a pinch of salt, and a crushed garlic clove for extra flavor.
On a baking sheet, toss the green beans with a drizzle of olive oil, salt, and pepper.
Place both the marinated chicken and the green beans in the oven. Roast the chicken for about 20-25 minutes until cooked through, and roast the green beans for about 15 minutes until tender and slightly crisp.
Serve the roasted chicken alongside a generous portion of creamy garlic mashed potatoes and the roasted green beans for a balanced, satisfying meal.