Is cauliflower cheese a proper noun?
No, the term 'cauliflower cheese' is a common noun.
A proper noun is the name of a specific person, place, thing; for example:
All contain all five vowels exactly once.
Would cauliflower cheese have a capital letter if it was used in a sentence?
No.
Cauliflower cheese is not a proper noun and only the word cauliflower would have a capital on the first letter if it started a sentence.
What did Salvador Dali fill with cauliflower?
In December 1955, Dali gave a lecture at the Sorbonne in Paris. The lecture was titled 'Phenomenological Aspects of the Paranoiac Critical Method', and was about the morphological connections he had identified amongst cauliflowers, sunflowers, rhinoceros horns and Jan Vermeer's painting, The Lacemaker. Dali arrived at the Sorbonne in a white Rolls Royce Phantom II that belonged to his friend, the French painter Georges Mathieu. Prior to the event, Mathieu had procured 500 kg of cauliflowers from Les Halles and filled the Royce Royce with the cauliflowers to make Dali's arrival a real spectacle! After the lecture, the cauliflowers were donated to a Catholic sisterhood.