Heat oil in a large pot over medium heat. Once hot, add onions and turn heat down slightly. Saute onions for 5 to 6 minutes until softened. Add celery and continue to cook 4 to 5 minutes. Add garlic and cook for 1 additional minute. Add cauliflower, potatoes, and stock (stock may not cover vegetables). Stir and bring to a boil. Turn soup down to a simmer, cover with a lid, and cook for 15 to 20 minutes until everything is very tender when poked with a fork.
Using an immersion blender, blend soup until as smooth as possible. (If using a stand blender, remove soup from heat and cool slightly before blending.) Soup will be quite thick; add water or stock as desired.
Serve while hot with your favorite baked potato toppings.
Recipe provided by Food Doodles
Nutrition information based on soup without toppings.