Turn your oven to 250C. Chop your onion in half lengthwise. Then peel and slice the onion finely into 1/2 moon shapes.
Place onion and sausages on a very large roasting tray. Drizzle with a little oil and pop in the oven. Set your timer for 5 minutes.
Meanwhile, chop the broccoli lengthwise into quarters. When the timer goes, toss the broccoli in with the sausages and onion and return to the oven. Set your timer for 15 minutes.
While the sausages are cooking, remove the stems from the kale and tear each leaf into 3-4 pieces, discarding the stem.
When the 15 minutes is up. Toss in the kale with the sausages and veg and pop back in the oven. Set your timer for a final 5 minutes.
After the timer goes, everything should be cooked and the sausages browned. If not, pop back in the oven for another 5 minutes.
To serve divide sausages and veg between 2 plates. Top with pesto and shaved parmesan (if using).