Simply Tomato Soup with Roasted Tomato Garnish

(generously serves 4)
2 lbs ripe field-ripened Roma (or other meaty) tomatoes, seeded
1 medium white onion
2 tbs butter
1 cup chopped fresh basil
approximately 1-2 tbs sugar
kosher salt/fresh ground pepper
Roughly chop onions. Melt butter in a large pot over medium heat. Add onions and cook until softened. Core and coarsely chop tomatoes. Add to onions. Heat until the juices from the tomatoes begin to simmer. Reduce heat to low. After about 15 minutes, add basil. Using an immersion blender, blend until smooth. Add sugar, adjusting amount depending on tomatoes’ sweetness. Season with salt and pepper to taste.
For roasted tomato garnish: Halve several (about 3 per serving) red and yellow grape tomatoes. Drizzle with extra virgin olive oil, sprinkle with kosher salt and fresh ground pepper. Roast tomatoes in oven, at 350F, until soft. Place a few of the roasted grape tomatoes on top of bowls of soup. Drizzle soup with olive oil.
Serving suggestions: Serve tomato soup with slices of crusty bread topped with Port Salut, or other favourite, cheese. Sprinkle with kosher salt and fresh ground pepper, then toast in the oven until cheese is hot and bubbly.