01 -
Melt butter in a large pot over medium-high heat. Add onion and saute until slightly browned and caramelized, about 10 minutes.
02 -
Reduce heat to medium, add garlic and saute 30 seconds. Add flour and cook, stirring constantly, 1 minute.
03 -
While whisking slowly pour in chicken broth. Cook and whisk until flour has blended in, about 1 minute.
04 -
Add tomatoes, basil, parmesan, sugar and season with salt and pepper to taste. Bring to a light simmer.
05 -
Reduce heat to low, cover and let simmer, stirring occasionally. Scrape along bottom of pot when stirring. Cook about 25-30 minutes until tomatoes break down.
06 -
Remove from heat. Remove basil sprigs and parmesan rind then use an immersion blender to puree soup until smooth.
07 -
Serve warm topping servings with swirl of cream if desired and chopped basil.