Whip heavy cream with powdered sugar and vanilla extract in a small bowl until soft peaks form. Refrigerate until ready to use.
In a medium saucepan, combine granulated sugar, light corn syrup, and water over medium heat. Stir until sugar dissolves, then stop stirring and simmer until deep amber color forms, about 8 to 10 minutes.
Carefully pour in warmed heavy cream; mixture will bubble vigorously. Add cubed butter and salt, stirring until smooth. Remove from heat and stir in vanilla extract.
Pour a thin layer of caramel into a parchment-lined square pan. Let it set slightly for 5 to 7 minutes.
Pipe or dollop the chilled vanilla cream evenly over the set caramel layer.
Pour the remaining caramel over the vanilla cream layer, covering completely. Smooth the surface and let cool to room temperature or refrigerate until firm.
Once fully set, remove from the pan and cut into squares. Optionally, sprinkle with sea salt or dip in melted chocolate before serving.