Preheat oven to 425°F and line a large baking sheet with parchment paper.
Arrange halved tomatoes, onion quarters, and garlic cloves on the baking sheet, drizzle with olive oil, and season with salt, pepper, and oregano.
Roast for 35-40 minutes until tomatoes are caramelized and slightly charred at the edges.
Transfer roasted vegetables to a large pot and add the vegetable broth, then bring to a simmer over medium heat for 5 minutes.
Remove from heat and stir in fresh basil leaves, then use an immersion blender to puree until smooth and creamy.
Stir in honey to balance acidity, adjust seasoning if needed, and serve hot with additional fresh basil for garnish.