Preheat the oven to 350°F (175°C). Coat a large baking dish with 1 tablespoon of the olive oil and arrange the thin lemon slices in a single layer on the bottom.
In a large bowl, whisk together the remaining 5 tablespoons olive oil, the juice from 1 lemon, minced garlic, kosher salt, and black pepper until combined.
Add the trimmed green beans to the bowl and toss to coat in the oil mixture. Use tongs to transfer the beans and place them on top of the lemon slices in the baking dish.
Place the quartered red potatoes into the same oil mixture and toss to coat. Arrange the potatoes over the green beans along the inside edge of the dish.
Coat each chicken breast in the remaining oil mixture, then place the breasts in the baking dish. Pour any leftover oil mixture over the chicken.
Bake at 350°F (175°C) for 1 hour to 1 hour 15 minutes, or until the potatoes and vegetables are tender and the chicken is cooked through (internal temperature 165°F / 74°C).
Remove from the oven and let rest a few minutes before serving warm.
