Mix 400ml water with Worcestershire sauce and treacle then freeze for 4 hours.
Rinse sweetbreads under cold water and soak in fresh water for 3 hours.
Simmer milk with rosemary and salt then poach the sweetbreads until the milk simmers again.
Strain the sweetbreads, remove skin and fat, and cut into 1cm pieces.
Heat oil in a lidded pan, pop the corn, then crush kernels in a food processor.
Heat a deep-fat fryer or heavy pan with oil to 180°C.
Whisk tempura flour and sparkling water into a smooth batter.
Dredge sweetbreads in seasoned flour, dip in batter, and coat with crushed popcorn.
Deep-fry until golden-brown and serve with the scraped Worcestershire ice.