Preheat the oven to 400°F (200°C).
Place the beet chunks on a baking sheet, drizzle with olive oil, and toss to coat evenly.
Roast for 35 to 40 minutes, or until the beets are tender.
Meanwhile, heat a tablespoon of olive oil in a large pot over medium heat.
Add the onion and carrot, cooking for 5 to 6 minutes until softened.
Stir in the garlic and thyme, cooking for 1 minute until fragrant.
Add the roasted beets and vegetable broth.
Bring the soup to a gentle boil, then reduce the heat and simmer for 15 minutes.
Remove from the heat and blend until completely smooth using an immersion blender or countertop blender.
Stir in the crumbled feta and heavy cream, if using, until fully incorporated.
Taste and adjust the seasoning with additional salt and pepper if needed.
Serve warm, garnished with extra feta, fresh thyme, and a light drizzle of cream.