Step 1

Heat a large pot over medium heat. Melt the butter, then add the chopped onions. Add 1 teaspoon salt and 1 teaspoon pepper. Saute the onion about 8 minutes until they turn translucent, stirring occasionally. Add in the garlic and cook for 30 seconds, or until fragrant.

Step 2

Sprinkle in the flour, and stir to cook the flour for 1 minute. Will look like a paste. Slowly stir in the chicken stock, whisking the whole time so the flour doesn't clump. Then add the canned tomatoes and basil. You can either transfer to a slow cooker and cook over low for 4 hours or high for 2 hours, or cook it on the stove top by bringing it to a boil, then cover and reduce heat to low and cook for 20 more minutes.

Step 3

Remove the lid, and either use an immersion blender or stand blender (careful when blending hot liquids in a stand blender!). Blend until the soup is creamy. Then stir in the parmesan cheese and heavy cream. Heat soup for another 5-10 minutes, or until the cheese is melted and the soup is warm. Taste for salt and pepper. Serve warm.

Step 4

Leftovers will keep for 1 week in an airtight container. Freezes beautifully. See notes for freezing tips.