Preheat oven to 400°F (200°C).

Toss the heirloom tomatoes and whole head of garlic with olive oil and roast for 30-40 minutes, or until tomatoes are softened and slightly caramelized.

In a large stockpot, brown the sliced onions until lightly golden.

Add the vegetable stock and bay leaves to the pot. Squeeze the roasted garlic from its skin into the stock.

Add the roasted tomatoes to the stockpot. Bring to a simmer and cook for 15 minutes.

Remove bay leaves. Carefully blend the soup using an immersion blender or transfer to a regular blender. Blend until smooth.

Slice the sourdough bread and brush with olive oil. Sprinkle with grated Romano cheese.

Toast the bread until golden and the cheese is melted and bubbly.

Serve the soup hot with the Parmesan toast for dipping. Garnish with fresh basil and a drizzle of olive oil.