You absolutely can, with one caveat. You have to freeze it before adding the sour cream because milk does not thaw well. Divide the cauliflower into portions,  place it in a freezer bag and freeze. To use after freezing, thaw overnight in the fridge, add the sour cream, and blend. If you're in a hurry, just use an immersion blender to quickly whisk the sour cream and spices together, and you're good to go.