Preheat your oven to 400°F (200°C). This will ensure your veggies roast to perfection.
In a large mixing bowl, combine the drained chickpeas, sliced fennel, red onion, cherry tomatoes, and olives. Drizzle with olive oil and season with sea salt, black pepper, garlic powder, dried thyme, and chili flakes (if using). Toss well to coat all the ingredients evenly.
Add the sliced vegan sausages to the vegetable mixture. Gently toss everything together once more to ensure the sausage is well-distributed among the veggies.
Spread the mixture evenly on a large sheet pan. Roast in the preheated oven for about 25-30 minutes, or until the vegetables are tender and starting to caramelize, stirring halfway through for even cooking.
While the veggies are roasting, prepare the pesto cream. In a bowl, whisk together the vegan pesto, cashew butter or tahini, lemon juice, and water. Adjust the consistency as needed by adding more water to achieve your desired creaminess. Season with sea salt and black pepper to taste.
Once the veggies and sausage are beautifully roasted, remove the sheet pan from the oven. Serve the mixture warm over a bed of baby arugula, drizzled generously with the pesto cream. Pair with ciabatta bread for a complete meal.