01 -
In a big pot, set butter to melt on medium-high. Toss in the onions and cook for about 10 minutes until they're golden and caramelized.
02 -
Lower the heat to medium. Stir in garlic and let it cook for roughly 30 seconds. Add the flour, stirring nonstop for a minute.
03 -
Slowly pour chicken broth while whisking so everything mixes smoothly. Keep stirring and cook for about a minute until blended.
04 -
Add in tomatoes, basil, the parmesan rind, sugar, then sprinkle in salt and pepper. Let everything come to a mild simmer.
05 -
Turn down to low, put the lid on, and let it simmer. Stir every so often, scraping the bottom. Cook for about 25 to 30 minutes until the tomatoes are softened.
06 -
Take it off the heat, pulling out the basil and parmesan rind. Use an immersion blender to puree everything into a smooth mix.
07 -
Serve hot, adding a swirl of cream and chopped basil on top if you'd like.