Combine the water, sugar and corn syrup or liquid glucose in a medium-size, heavy-based saucepan over medium heat. Stir until the sugar has dissolved and then bring to a bubbling boil. At this point, stir in the butter and leave to cook until the resulting caramel reaches 147 °C (296 F) on a sugar thermometer.
Remove from the heat, then add the vanilla extract, spices and bicarbonate of soda and stir quickly to coat. Immediately add the nuts and give it another super quick stir and then tip out onto the prepared baking tray. Spread it as evenly as possible.
Leave the brittle to cool and harden completely before breaking into shards and storing in an airtight container. If you leave it out it will attract moisture and start to soften.
Notes
Store any leftover brittle in an airtight container.