Line an 8X8 heat proof dish with parchment paper and coat it with non stick spray.
Place butter and heavy cream in a small sauce pan over medium heat. Heat until butter is melted. Don't bring the mixture to boil. Add Salt to butter heavy cream mixture. Turn the heat off.
In a big pot, mix sugar, corn syrup and water. Using a spoon stir it until forms a paste. Using a wet brush, wipe down the sides of the pot so there are no sugar crystals left on the sides.
Turn the heat on to medium high and clip an instant-read thermometer to the side of the pot. Don not stir the mixture. Bring the mixture to boil and let it boil until it reaches 285-290°F.
Turn the heat off.
Whisk in the cream and butter mixture slowly to the pot. It will boil rapidly and triple in size. Stop whisking once all the cream is all in.
Turn the heat on to medium high and clip the instant thermometer again. Bring the caramel to a boil and let it boil until it reaches 240°F.
Turn the heat off and take the thermometer out of the pot.
Pour the caramel into the lined dish and let it sit in the room temperature for at least 2 hours or until set completely.
Cut into rectangles or squares and wrap them in wax paper or candy wrappers. Keep the caramels in a container with a lid.