Toffee

Bahan-bahan (16 porsi)

• 1 cup (226g) unsalted butter, cut into pieces
• 1 cup (200g) granulated sugar
• 1/4 cup water
• 1 teaspoon fine sea salt
• 1 teaspoon vanilla extract
• 1 cup semisweet chocolate chips
• 2 tablespoons finely-chopped almonds or walnuts, for topping (optional)
• flaky sea salt, for topping (optional)