This soup requires minimal ingredients but yields such amazing results! When you combine several pounds of fresh tomatoes, several cups of fresh basil and a fair amount of garlic you know it's got to be good.
Prepared grilled cheeseor grilled cheese croutons (optional), see notes
Preheat oven to 425 degrees. Place tomatoes on a rimmed baking sheet and toss with 3 Tbsp olive oil then season with salt and pepper (place Roma halves cut side upright).
Place onion slices and garlic on a rimmed half sheet and toss brush with remaining 1 1/2 Tbsp olive oil on all sides, sprinkle with salt and pepper.
Place baking sheet with tomatoes and half sheet with onions in oven side by side and roast garlic 15 minutes (or until just golden) and remove, roast onions 30 - 35 minutes (until edges are golden brown) and remove, and tomatoes 40 - 45 minutes until slightly browned.
Pour tomatoes, onions and garlic into a large pot. Add vegetable broth and about 3/4 of the basil. Season with salt and pepper to taste.
Bring to a boil, cover, then reduce heat and simmer 20 minutes.
Blend soup with an immersion blender or in small batches in a blender (only fill blender half full and remove center insert and cover with a kitchen towel). Serve warm topped with remaining basil (chopped).
For the grilled cheese or grilled cheese croutons:
Use 6 slices of hearty sourdough, wheat or white bread. Brush outsides of all slices with 1/2 Tbsp of butter on each. Sprinkle 1/2 cup (2 oz) shredded mozzarella or cheddar over non-buttered sides of three slices. Top with remaining 3 slices of bread with buttered side up. Cook in a skillet over medium heat, reducing to medium-low as needed, until bottom is golden brown. Flip and cook opposite side until golden. Cut in half if serving as a sandwich or if serving as croutons in the soup cool just slightly then cut into squares.
Optionally you can pull peels from tomatoes if preferred. You can also leave basil on the sprigs then remove sprigs before blending if desired.
For a creamy tomato soup you can add 1/2 cup to 1 cup heavy cream to the soup. For a cheesy flavor you can serve with finely shredded parmesan cheese.
Recipe makes about 9 cups soup.
Grilled cheese not included in nutrition estimate.