This paleo cauliflower soup takes some time, but most of it's hands off. Do also take the time to garnish this soup properly. You'll be rewarded with the creamiest, most flavorful roasted cauliflower soup you can imagine.
Toss the cauliflower florets with 1 tbsp olive or avocado oil and spread on the baking sheet. Slice off the top of the head of garlic and rub another 1 tbsp of oil into the exposed garlic cloves. Wrap the garlic in aluminum foil and add it to the baking sheet.
Roast the cauliflower and garlic until the cauliflower is golden brown and tender and the garlic is soft and squeezable. This will take anywhere from 40-60 minutes. The cauliflower may finish roasting before the garlic, so check it every 5 minutes after the 40-minute mark.
Halfway through the roasting process, start the onions. Heat a large soup pot or dutch oven over medium heat. Add 1 tbsp of butter or ghee and heat until it melts. Add the onions to the pot, stir to coat in the fat, and then cover and sweat, stirring occasionally, until the onions are soft and translucent about 20 minutes. If the onions finish before the cauliflower and garlic, turn the heat down to low and keep covered, stirring occasionally.
Add the roasted cauliflower to the pot, reserving about a cup of the tiniest florets for garnish. Allow the garlic to cool for a few moments, then squeeze the roasted garlic cloves out of the papery shells and add to the pot.
Add the diced potato and enough broth to just barely cover the vegetables (I used about 4 cups). Give everything a quick stir and then toss in a sprig of thyme.
Increase the heat to medium-high, bring the liquid to a boil, then reduce heat to medium-low and simmer until the potatoes are soft, about 20 minutes.
While the soup is simmering, heat a small skillet over medium high heat. Add the pine nuts to the pan and toast, stirring continuously, until the pine nuts are lightly golden brown. Remove from heat and set aside.
Once the potatoes are soft, remove the thyme sprig. Blend the soup with an immersion blender (or in a blender in batches) until smooth and creamy. If the soup is too thick, add a bit of extra stock or water, 2 tbsp at a time. Taste for seasoning and add salt and pepper to taste.
Ladle the soup into bowls and garnish with olive oil, cauliflower florets, pine nuts, and fresh thyme leaves. Serve immediately. This soup keeps in the fridge for up to 5 days, or in the freezer in an airtight container for up to three months.