Preheat oven to 375 degrees Fahrenheit. Line a rimmed baking sheet with parchment paper or foil.

Cut cauliflower into florets and place on prepared baking sheet in a single layer. Season with kosher salt, ground black pepper, and olive oil. Add the garlic and shallots. Gently combine seasonings and aromatics together with the cauliflower until everything is well coated.

Roast for about 20 to 30 minutes until cauliflower is knife tender and the edges begin to brown and caramelize.

Remove from oven and allow to cool slightly for 5 minutes. Spoon the roasted vegetables into the base of a high-powered blender or food processor. Pulse to begin to break up the roast cauliflower, shallots, and garlic. Then, with the machine running, gently pour in the vegetable or chicken stock slowly in a steady stream. Blend or process until the cauliflower mixture is smooth. Taste and adjust seasoning as desired.

Spoon the roast cauliflower puree into a serving bowl. Serve immediately.