Step 1: Prepare Your Workspace - Gather all your ingredients and tools. Line a baking sheet with parchment paper and set it aside.
Step 2: Combine Ingredients in a Saucepan - In a heavy-bottomed saucepan, combine the butter, sugar, corn syrup, and water. Stir over medium heat until melted.
Step 3: Bring to a Boil - Increase heat and bring to a boil without stirring. Monitor the temperature closely with a candy thermometer.
Step 4: Cook to Hard Crack Stage - Cook until the thermometer reads 300°F (hard crack stage), about 15-20 minutes.
Step 5: Pour onto Parchment Paper - Pour toffee mixture onto the prepared baking sheet and spread evenly if necessary.
Step 6: Add Chocolate Chips - Allow to cool for about 5 minutes, then sprinkle chocolate chips on top and let them soften.
Step 7: Spread the Chocolate - Spread the melted chocolate evenly over the toffee using a spatula.
Step 8: Top with Nuts and Sea Salt - Sprinkle nuts and sea salt flakes on top for a sweet and salty finish.
Step 9: Cool Completely - Let toffee cool at room temperature for 1-2 hours until set.
Step 10: Break and Serve - Once cooled, break into pieces and serve or package for gifts.