Step 1

Pour the sugar into a large, heavy saucepan.

Step 2

Heat over medium-high heat, whisking it regularly. The sugar will form clumps and puddles, but just keep whisking it until all of it has melted.

Step 3

Once all of the sugar has melted, stop whisking it.

Step 4

Keep cooking the sugar until it reaches a deep golden amber color. Watch the sugar closely as it could easily overcook.

Step 5

Once the caramel is deep golden amber, add the butter, and whisk until it is completely incorporated. The caramel will bubble up, so be careful.

Step 6

Remove the pan from heat.

Step 7

Slowly stream the cream into the caramel, whisking to combine. The caramel will bubble up again, so be careful.

Step 8

Once the cream has been incorporated, whisk in the vanilla and fleur de sel.

Step 9

Let the caramel sit for 10-15 minutes.

Step 10

Pour into a glass jar, and let cool to room temperature (uncovered).

Step 11

The caramel can be refrigerated for up to 4 weeks.

Step 12

Warm before using.