Peanut brittle

Ingredients

• 40 ml water
• 145 g caster sugar
• ½ tsp salt
• 105 g liquid glucose
• 100 g roasted unsalted peanuts, skinless, roughly chopped
• 20 g unsalted butter, softened
• 1 vanilla bean, cut and scraped
• ½ tsp bi-carb soda, sieved