Preheat the oven to 400°F (200°C).
Slice the top off the garlic head to expose the cloves.
Place tomatoes and garlic on a baking sheet, drizzle with 1 tablespoon olive oil.
Roast in the oven for about 30-35 minutes or until the tomatoes are soft and the garlic cloves are caramelized.
In a large pot, heat the remaining olive oil over medium heat.
Add onions and sauté until translucent.
Squeeze the roasted garlic cloves out of their skins and add to the pot.
Add roasted tomatoes, breaking them up with a spoon.
Pour in the vegetable broth.
Stir in the salt, black pepper, dried basil, and dried oregano.
Bring the mixture to a boil, then reduce heat and simmer for 10 minutes.
Using an immersion blender or a stand blender, puree the soup until smooth.
Stir in the fresh basil and serve hot.