Heat the olive oil in a large stockpot or Dutch oven over a medium heat. Add the chopped onion, carrots, and celery. Cook, stirring occasionally, for 8-10 minutes until the vegetables have softened and the onion is translucent. Don't let them brown.

Add the minced garlic and dried oregano to the pot and cook for another minute until fragrant. Be careful not to let the garlic burn.

Pour in the two tins of tomatoes, using a wooden spoon to break up the whole tomatoes against the side of the pot.

Add the vegetable stock, caster sugar, salt, and black pepper. Stir everything together well.

Bring the soup to a simmer, then reduce the heat to low, cover the pot with a lid, and let it gently bubble away for 20 minutes. This simmering time is crucial for the flavours to develop and deepen.

Remove the pot from the heat. Using an immersion blender, carefully blitz the soup directly in the pot until it is completely smooth and velvety. If you don't have an immersion blender, you can transfer the soup in batches to a regular blender, but be sure to let it cool slightly first and cover the lid with a tea towel to prevent any hot splashes. What works best for me is starting the immersion blender on low and gradually increasing the speed.

Return the pot to a very low heat (do not let it boil). Slowly pour in the double cream, stirring continuously until it's fully incorporated.

Taste the soup and adjust the seasoning if necessary. You may need another pinch of salt or pepper.

Ladle the hot soup into bowls, tear over some fresh basil leaves, and serve immediately.