Put the can into a pot and fill in enough water so that 3/4 of the can is in water. Bring water to the boil, cover and boil for about 1 1/2 hours. Take out can, let it cool down and open.
Whisk the eggs in a deep dish. Warm the milk and vanilla sugar and put it in a second deep plate. Halve the brioche slices and turn them first in the milk, then pull them through the eggs.
Melt the butter in portions in a pan. Fry the brioche slices for 3-4 minutes while turning them over until golden brown. Dust the brioche with icing sugar and serve with about half of the caramel sauce. Use the rest of the caramel sauce for other purposes.