Preheat the oven to 425 degrees F (220 degrees C). Line a sheet pan with foil.

Spread vegetables out on the prepared pan. Drizzle with olive oil; toss to coat. Sprinkle salt and Italian seasoning evenly over vegetables.

Roast vegetables in the preheated oven for 20 minutes.

Fill a blender halfway with roasted vegetables and accumulated juices. Pulse a few times before blending completely for 45 seconds. Pour into a saucepan and repeat if necessary.

Add water and cream to the soup, stir to combine, and cook until heated through, about 3 minutes. Adjust seasonings to taste.