Preheat your oven to 400°F (200°C) and grease a baking tray or line with foil. Set aside.
Brine the chicken by filling a large bowl with lukewarm water. Stir in a handful of salt until it dissolves and then add your chicken breasts. They should sit in the water for at least 15 minutes. Rinse the chicken breasts when done and set aside.
In a small bowl, mix together the melted butter, chicken broth, chopped garlic, garlic powder, thyme, and rosemary. Set aside.
Place chicken on a greased baking sheet and place the cauliflower florets, zucchini, onion, and bell peppers all around the chicken. Pour over half of the sauce and toss everything until it is well coated. Arrange into a single layer again. Sprinkle over some salt and pepper to season.
Bake in the preheated oven for 15 minutes or when vegetables just start to become golden.
Carefully remove the baking tray from the oven and flip the chicken breasts over. Pour the rest of the garlic herb butter sauce over the vegetables and toss well to coat. Return the baking tray to the oven for another 10 minutes, or until chicken is cooked through and vegetables are softened.
Remove the baking tray from the oven and cover the chicken breasts with foil for 10 minutes before cutting and serving with pan juices.
Optional: You can broil the vegetables for a couple of minutes here if needed to add extra color and crispness.