Place a large nonreactive pot or enameled Dutch oven over medium heat. Melt the butter, then add the finely chopped onions. Cook for 10–12 minutes, stirring occasionally, until the onions become soft and lightly golden.
Add the minced garlic and cook for about 1 minute, stirring frequently, until fragrant.
Pour in the crushed tomatoes and their juice, followed by the chicken stock. Add the chopped basil, sugar, and black pepper. Stir until everything is well combined.
Bring the mixture to a gentle boil. Reduce the heat, partially cover the pot, and simmer for about 10 minutes so the flavors can develop.
For a rustic soup, leave some tomato and onion pieces intact. For a smooth and creamy texture, carefully blend the soup with an immersion blender until it reaches your preferred consistency. If using a countertop blender, work carefully in small batches.
Return the blended soup to medium-low heat. Stir in the heavy whipping cream and freshly grated Parmesan.
Bring the soup back to a gentle simmer without vigorously boiling it. Taste and adjust the salt, pepper, sugar, or cream as needed.
Serve the Easy Tomato Soup Recipe warm with additional Parmesan and fresh basil on top.