Preheat the oven to 450 degrees Fahrenheit.

Place the veggies on a sheet pan or two, if necessary. Make sure they aren’t packed together because they’ll end up steaming instead of roasting. Season with the olive oil, salt, and pepper and roast for 30 minutes.

Add the roasted veggies, veggie broth, and cauliflower, and basil to a blender and blend. Alternatively, add to a pot and use an immersion blender to blend until smooth.

Ladle soup into bowls and serve topped with additional sliced basil.