Lightly grease an 8x8 or 9x9 baking dish (I used baking spray with flour).
In a saucepan, combine the sugar, water and corn syrup. Cover the pan and bring to a boil over high heat. Once some steam has developed in the pan, remove the lid (steam will help prevent crystallization). Continue to boil until the caramel turns a deep honey color, approximately 10-15 minutes.
While the sugar is cooking, combine the butter and cream in a microwave safe bowl. Microwave for 30 seconds at a time until the butter is melted.
When the caramel begins to darken, carefully but swiftly add the cream and butter. The mixture will steam and bubble up so pull your hand away. Use a heat resistant spatula to stir the mixture and add the salt once the bubbling has calmed down a bit.
Place a candy thermometer in the saucepan and stir frequently until the mixture reached 260 degrees.
Pour the caramel into the prepared baking dish and allow it to cool completely. Sprinkle smoked salt on top.
Use a warm knife to cut caramels into small squares or rectangles. I used a ruler to draw guides first. Caramels will keep at room temperature for a few weeks.