Preheat oven to 425°F (220ºC).
Place tomatoes, onions and garlic pieces in a 9x13-inch baking dish and lay the sausages across the top. Toss in a few sprigs of thyme and rosemary then drizzle with olive oil and season with salt and pepper.
Roast for 35-40 minutes until the sausages are golden. Remove dish from oven and stir in white beans. Return to oven and continue to roast for another 15-20 minutes until the beans are cooked through. Transfer to serving plates and devour immediately.