Preheat oven to 400 degrees. Slice the top end off the head of garlic, then add to a parchment-lined baking sheet with tomatoes and yellow onion. Season with salt and pepper, then drizzle with olive oil
Bake for 25-35 minutes until vegetables have softened.
Transfer tomatoes and onions to a blender and squeeze garlic from head of garlic.
Add vegetable broth and blend until smooth
Butter the bread slices, then place them in a pan. Add sliced cheddar cheese on top and cover with another slice of bread. Cook until golden brown.
Slice grilled cheese into croutons
Ladle soup into bowls and top with croutons and fresh basil
