Streuselkuchen (German Crumb Cake) vs Gypsy Tart

Both desserts rely on cold butter rubbed into flour, but they put it to very different work. In Streuselkuchen it forms coarse, distinct crumbs that bake golden over a soft yeast dough enriched with milk, egg and a little softened butter, with lemon zest as an optional lift. In Gypsy Tart it makes a firm, blind-baked shortcrust bound with egg yolk, holding a filling of evaporated milk and dark brown sugar whisked until fluffy and coffee-coloured. One is crumbly and bready; the other is intensely sweet, airy and gently set.