Line an 8-inch square baking pan with lightly oiled parchment paper.
Combine the heavy cream, cubed butter, and sea salt in a medium saucepan over medium heat and bring it to a boil. Once it's reached a boil, remove it from the heat and set it aside.
In a separate medium saucepan, combine the sugar, corn syrup and water and place it over medium heat, bringing it to a boil and swirling until it's golden brown in color. Do not stir.
Carefully stir the cream mixture into the sugar mixture. Be careful, as it will bubble up. Continue cooking the mixture, stirring occasionally, until it reaches 248ºF on a thermometer, about 12 minutes.
Once the mixture has reached 248ºF, immediately pour it into the prepared pan and let cool for at least 2 hours.
Once the caramel has cooled completely, use a sharp knife to cut the block into 40 candies. Store candies in an airtight container until ready to eat.