I froze it until it was solid, and took that. When they questioned me about it, I pointed out that it was not a liquid, and got away with it.
Someone (successfully) worked this scam in Germany, garnering export subsidies for dairy solids which were higher than for dairy products in liquid form.
Froze the milk, trundled across the border to the Czech Republic (probably Czechoslovakia back then) and let it thaw.
Went on for yonks until they changed the law...