1/3 cup water
1/4 cup corn syrup
1 1/2 cups sugar
1 cup heavy cream
1/4 cup unsalted butter
1/2 tsp salt
In a large saucepan, combine water, corn syrup and sugar. Bring to a boil over high heat, then continue to boil until caramel turns a deep honey color (10-14 minutes).
While sugar cooks, combine cream and butter in a microwave-safe bowl and cook for 1-2 minutes on high heat, until butter is melted. Set aside.
When sugar is a deep honey color, pour in cream mixture. Caramel will bubble up vigorously. Stir until bubbles subside slightly, then stir in salt. Attach a candy thermometer to the side of the pan and continue to cook, stirring regularly with a silicone spatula, until caramel reaches 260F (5-10 minutes).
Pour caramel into a greased pyrex and cool. Once firmed you should be able to roll it out.
Melt chocolate of your choice and brush onto molds. Chill. Add cut caramel chunks to mold and pour more melted chocolate on top.