In a small saucepan over medium heat, add the butter, cream, sea salt and vanilla and bring just barely to a boil. Reduce the heat to simmer, stir to dissolve the salt and hold at simmer to keep warm until needed.
In a 3 to 4 quart saucepan, add the corn syrup and sugar over medium heat. Allow the sugar to melt slowly, disturbing it as little as possible.
When you see liquid forming around the perimeter of the pan use a spatula to push the sugar toward the center and continue with this process breaking up any clumps. This will take a little patience and you will be tempted to stir and stir but resist the urge. If you stir it too much, the sugar will clump up before it has a chance to melt. If this happens turn the heat down very low and let it melt slowly without stirring.
As soon as the sugar is completely melted and the syrup is a nice amber color, remove it from the heat. It should smell like caramel at this point.
Slowly pour the hot cream mixture into the melted sugar whisking as you pour. Be very careful as there will be aggressive bubbling and it will appear that it will bubble over the pan. Keep stirring and it will settle down again. Continue to whisk the caramel to incorporate it well. Allow the sauce to cool for 10-15 minutes before pouring it into a container.
This sauce will appear thin until it cools down. Store it in the refrigerator for up to 3 weeks or in the freezer for 3 months. To serve, remove from the refrigerator and set the container into a dish or pan of hot tap water for 5 minutes and it will soften to a spoonable consistency.
Notes
Start with a solid pan. Choose a heavy-bottomed saucepan with plenty of room. The caramel will bubble up once the cream goes in.Be patient with the sugar. Let it melt gradually around the edges before nudging it toward the center. Rushing or stirring too early can make it clump.Gently move, don’t mix. As the sugar liquefies, use your spatula to ease the unmelted parts inward rather than stirring .Use color as your guide. Look for a deep amber tone instead of watching the clock. That’s when you’ll get rich flavor without bitterness.Add the cream slowly. Pour in a thin stream while whisking nonstop; it’ll foam up but smooths out quickly as it comes together.Expect it to thicken as it cools. It’ll seem thin right off the heat but sets into the perfect drizzle texture once it rests.Warm ingredients. Room-temperature cream and butter prevent seizing and make the sauce come together seamlessly.Cleanup made easy. If any caramel hardens on your utensils, soak them in hot water.Store and reheat gently. Keep it in a glass jar in the fridge for up to two weeks, and rewarm it slowly over low heat or in short microwave bursts until pourable again.