Divide the cauliflower into small florets. Chop the onion and garlic. Cut the carrots into thick slices.
Braise the vegetables in rapeseed oil and deglaze with broth. Cook until the vegetables are tender. Puree together with cashew butter and yeast flakes in a blender (or with the hand blender) until finely creamy. Season to taste with freshly ground pepper.
Briefly heat the sauce in the saucepan and stir in the spinach until it has collapsed.