Line a 9 inch square pan with nonstick foil.

In a 3 quart nonstick saucepan, stir the softened butter, sugar, corn syrup and condensed milk together until fully blended. Turn on the heat and set it to medium. Cook, stirring every so often with a wooden spoon or heat proof scraper, until boiling (about 6 minutes)

Reduce mixture to a very soft boil – a little over a simmer. Insert candy thermometer and heat to 240 (soft ball stage), stirring often and making sure the heat is rising slowly and steadily. This should take about 20 minutes, and towards the end you’ll notice the mixture darkening a bit. When mixture reaches about 240, remove from heat and stir in vanilla. Pour caramel into the pan. Let cool at room temperature for 2 hours, and then cover with melted chocolate.

Combine chocolate chips and coconut oil (or shortening) in a microwave-safe bowl and heat at 50% power, stirring every 30 seconds, until smooth and shiny. Pour chocolate over caramel.

Refrigerate until chocolate is set. When chocolate is set, lift from the pan and cut into squares.

Sprinkle with sea salt before serving.