Preheat the oven to 400 degrees F. Toss together the tomatoes, 1/4 cup olive oil, salt and pepper. Spread the tomatoes in 1 layer on a baking sheet and roast for 45 minutes.

Meanwhile in an 8-quart stockpot over medium heat, saute the onions and garlic with 2 tablespoons of olive oil, the butter, and red pepper flakes for 10 minutes, until the onions start to brown. Add the canned tomatoes, basil, thyme, and chicken stock. Add the oven-roasted tomatoes, including the liquid on the baking sheet. Bring to a boil and simmer uncovered for 40 minutes.

Pass through a food mill fitted with the coarsest blade or blend with an immersion blender. You can also blend up the soup in a blender or food processor a little at a time. If using a blender or food processor make sure soup is cooled so the pressure does not build up. After soup is blended, warm up again on stove. Taste for seasonings.