Heat a large, deep sauce pan over medium heat. Add butter, and melt until beginning to bubble.
Add quartered onions, cook for 4-5 minutes until softened and translucent. Add garlic, cook for about one minute, then add canned tomatoes, chicken broth, salt, and pepper. Stir to combine.
Add crushed red pepper and mint, and stir to mix into the other ingredients. Simmer, uncovered, for about 40 minutes.
Remove the soup from the heat, and allow to cool about five minutes. Use an immersion blender or transfer the soup to a food processor or blender, and blend until almost completely smooth.
Add the soup back to the pot it was cooked in, and stir in the heavy cream. Adjust with additional salt and pepper to fit your tastes, if necessary.
Garnish with chopped basil or parsley, a little grated parmesan cheese, and serve hot!
Notes
This soup will keep in the refrigerator for up to four days.