Preheat oven to 400 degrees. Spread tomatoes, onions, and peppers on 2 large baking sheets in a single layer and toss with ¼ cup olive oil, salt, and pepper and 2 T chopped basil. Roast for 20 minutes. Remove from oven and set baking she,et aside.

In a large Dutch oven over medium heat, 2 T olive oil and 2 T butter. Add  garlic saute until just soft and add artichoke hearts and saute for 5 minutes. Sprinkle in ½ T salt and some pepper. Add chicken stock, and roasted vegetables (including their juices. Raise heat to high and bring to a boil. Reduce and simmer for 30 minutes (uncovered). Use an immersion blender or Cuisinart to blend mixture until mostly smooth.  Add 1/2 and 1/2  to finish. Serve with a sprinkling of fresh basil and parm.