1.Preheat oven to 180°C. Line a large oven tray with baking paper.
2.Spread almonds in a single layer on tray. Bake 10-12 minutes, until lightly golden.
3.In a medium, heavy-based saucepan, combine sugar, water and vanilla. Stir over medium heat until sugar dissolves. Bring to the boil. Boil, without stirring, 8-10 minutes, until just turning golden around the edges. Remove and discard vanilla bean.
4.Gently stir almonds into toffee to coat nuts, along with butter and salt. Pour onto tray. Using a wooden spoon, spread nuts into a single layer. Set aside 30 minutes to cool and set.
5.Break up nuts and store in an airtight container.