Preheat the oven to 375°F (190°C).
In a small bowl, combine softened butter, 4 cloves minced garlic, and chopped parsley. Mix well.
Spread the garlic butter mixture evenly on each slice of French bread.
Place the bread slices on a baking sheet and bake for 10-12 minutes, or until the bread is golden and crispy.
While the bread is baking, heat olive oil in a large pot over medium heat.
Add diced onion and cook for 5 minutes until translucent.
Add 2 cloves minced garlic and cook for 1 minute until fragrant.
Pour in the crushed tomatoes and vegetable broth. Stir to combine.
Add sugar, salt, black pepper, and dried basil. Stir well.
Bring the soup to a boil, then reduce heat and simmer for 15 minutes.
Remove the soup from heat and use an immersion blender to puree until smooth. (Alternatively, carefully transfer soup in batches to a blender and puree.)
Return the soup to low heat and stir in the heavy cream. Heat through but do not boil.
Serve the hot tomato soup with warm garlic bread on the side.