Preheat your oven to 425°F.
In a shallow bowl, pour the buttermilk and lightly season with salt and pepper.
Place the chicken breast in the buttermilk, ensuring it's well-coated, and let it marinate for at least 20 minutes.
In a separate small dish, sprinkle the whole wheat flour.
Remove the chicken from the buttermilk, letting any excess drip off, then lightly coat it with the whole wheat flour.
On a baking sheet, toss the broccoli, diced carrot, and sliced bell pepper with olive oil, salt, and pepper.
Place the coated chicken breast on the baking sheet with the vegetables.
Roast in the oven for 20-25 minutes, or until the chicken is cooked through and the vegetables are tender and slightly crispy.
Serve warm and enjoy your balanced, crispy buttermilk chicken with roasted vegetables.