Preheat your oven to 325°F (165°C). Line a 9x9 inch baking pan with parchment paper, lightly greasing it.

Cream together the room temperature butter and granulated sugar until light and fluffy. Gradually add flour and salt, mixing until crumbly. Press into the prepared pan and bake for 30-35 minutes until golden. Allow to cool.

In a saucepan over medium heat, combine sweetened condensed milk, butter, corn syrup, and brown sugar. Stir constantly until it thickens, about 5 minutes. Remove from heat and stir in vanilla and salt, then pour over cooled crust.

Cover with plastic wrap and refrigerate for about 30 minutes to set the caramel layer.

In a microwave-safe bowl, combine chocolate and coconut oil. Heat in 30-second increments, stirring until melted and smooth. Pour over chilled caramel, smoothing evenly. Optionally sprinkle with flaky sea salt.

Return to the refrigerator for 45 minutes or until topping is firm. Lift bars out of the pan using parchment overhang and slice into squares.

Allow bars to sit at room temperature for 10-15 minutes for clean edges before serving.