In a saucepan, combine sugar, butter, and corn syrup. Cook over medium heat, stirring constantly, until the sugar is dissolved and the mixture comes to a boil.
Continue to boil, without stirring, until the mixture reaches 300°F (150°C) on a candy thermometer.
Remove from heat and stir in the pretzel twists until they are evenly coated.
Spread the mixture onto the prepared baking sheet and let it cool completely.
Once cooled, break the toffee into pieces and melt the chocolate chips. Drizzle melted chocolate over the toffee pieces and let set completely before serving.
Notes
Store in an airtight container at room temperature for up to a week.