In a dutch oven or stock pot, heat extra-virgin olive oil to medium heat. Add chopped onion. Sauté for about 8-10 minutes. Sweat; do not brown.
Add minced garlic and sauté for about a minute until fragrant. Stir to combine.
Add cauliflower florets, salt, Herbs de Provence and chicken stock. Stir to combine. Bring heat up to a boil. Cover and reduce to a simmer for 20 minutes.
Use the end of a sharp knife to pierce cauliflower to ensure tender before pureeing.
In a blender, purée soup in batches transferring to a large heat-proof bowl. Do not fill blender more than 1/3 full. Cover lid with a towel for extra precaution. Hot liquid expands in the blender. Combine batches and stir. Alternately puree with an immersion blender. Serve immediately.