Preheat your oven to 300°F (150°C). In a large mixing bowl, combine 1 cup of softened salted butter, 1 cup of powdered sugar, 2 cups of all-purpose flour, and 1 teaspoon of vanilla extract. Mix until the ingredients are well combined and crumbly. Press the mixture firmly into a greased 9x13” pan, spreading it evenly. Bake for 40 minutes or until the crust is golden brown, then remove it from the oven to cool slightly.

In a medium saucepan, combine 6 tablespoons of salted butter, ⅛ teaspoon of salt, ½ cup of light corn syrup, and 1 cup of granulated sugar, along with ½ cup of the heavy cream. Over medium heat, stir until the mixture begins to dissolve, then allow it to simmer gently without stirring. Use a candy thermometer to monitor the temperature, cooking until it reaches 235°F (113°C). Remove from heat, then stir in the remaining ½ cup of cream and 1 teaspoon of vanilla extract, pouring it immediately over the cooled crust.

In a microwave-safe bowl, combine 1 ¼ cups of milk or dark chocolate with ⅓ to ½ cup of heavy whipping cream. Microwave in short intervals of 30 seconds, stirring in between until the mixture is melted and smooth. Ensure it doesn’t overheat to prevent seizing. Once melted, gently pour the chocolate mixture over the caramel layer, spreading it evenly with a spatula for a beautiful finish.

Chill the assembled Twix Cookie Bars in the refrigerator for 3-4 hours, or until the chocolate layer is fully set and firm to the touch. Once set, gently lift the bars out of the pan using the edges of the foil. Slice them into squares or rectangles for serving, revealing the delicious layers inside. Enjoy these homemade Twix Cookie Bars with friends and family, or keep them all to yourself!