First, grease your 8-inch pan. Use a little bit of butter. Line it with parchment paper. Let the paper hang over sides. This helps you lift it later.
Mix Cream and Milk
Take a small microwave-safe bowl. Mix the cream and condensed milk. Warm it for one minute. Set it aside for later use.
Boil Sugar and Syrup
Put sugar and syrup in the saucepan. Add 1/4 cup of water. Stir it over medium heat. Let the sugar dissolve completely. Do not stir after it boils.
Cook to Golden Amber
Watch the sugar mixture closely. Let it turn a light amber. This takes about 10 minutes. Use your candy thermometer here. It should reach 320 degrees F.
Add Butter and Cream
Turn off the heat carefully. Slowly whisk in the butter cubes. Then pour in the warm cream. The mixture will bubble a lot. Be very careful with steam.
Reach the Final Temperature
Turn the heat back to medium. Stir the caramel constantly now. Reach 248 degrees F exactly. This is the "firm ball" stage.
Add Flavor and Cool
Remove the pan from the heat. Stir in the vanilla extract. Pour it into the prepared pan. Do not scrape the bottom. Let it sit for 20 minutes.
Sprinkle the Sea Salt
Now, sprinkle the sea salt over. The caramel should be slightly firm. The salt will stick nicely. Let it cool for 4 hours.
Cut into Pieces
Lift the caramel using the paper. Use a very sharp knife. Cut into small, even squares. You can wipe the knife often.
Wrap the Caramels
Cut small pieces of wax paper. Wrap each caramel square tightly. Twist the ends like a candy. This keeps them fresh and soft.
Notes
Use a high-quality candy thermometer.
Do not rush the boiling process.
Keep kids and pets away. Boiling sugar is very hot.
Use high-quality butter for better flavor.
Warm the cream before adding it. This prevents the sugar from seizing.
Wash down sugar crystals on sides. Use a wet pastry brush.
Wait for the caramel to set. Cutting too early is messy.
Store them in a cool place. They might melt in heat.
Use Fleur de Sel for salt. It has the best crunch.