Prepare your workspace by lining a large baking sheet with parchment paper.
This step is crucial for preventing the toffee from sticking.
In a large saucepan over low heat, melt the unsalted butter and sugar together.
Stir constantly until the mixture is smooth.
Add water and salt into the saucepan.
Increase the heat to medium and bring the mixture to a boil.
Cook until the candy thermometer reads 300°F (hard-crack stage).
Stir occasionally to avoid burning.
Stir in the roughly chopped almonds and vanilla extract just before removing the pan from heat.
Spread the hot mixture onto the prepared baking sheet.
Top with chocolate chips and cover with tin foil for 5 minutes.
Remove the tin foil and spread the melted chocolate evenly over the toffee.
Add extra almonds for topping.