(from The America's Test Kitchen Family Cookbook)
1/2 cup water
1 cup of sugar
1 cup heavy cream
pinch of salt
1/2 tsp vanilla extract
1/2 tsp fresh lemon juice
1- Pour the water into a medium saucepan. Add the sugar to the center of the pan, taking care not to let the granules adhere to the sides of the pan. Cover and bring to a boil over high heat.
2- Once boiling, uncover and continue to boil until the syrup is straw colored (about 7 minutes). Reduce heat to medium and continue to cook until the syrup is a deep amber color (1 to 2 minutes).
3- Meanwhile, bring the cream and salt to a simmer in a small saucepan. (If the cream simmers before the syrup reaches a dark amber color, remove from heat and cover to keep warm)
4- Remove the sugar syrup from heat. Very carefully, pour about ¼ of the hot cream into the syrup and let the bubbling subside (I don’t wait until all the bubbles are gone, just until they’ve calmed down otherwise the syrup gets too cold). Add the remaining cream, vanilla, and lemon juice and let the bubbling subside. (same thing here, let the bubbling calm down not stop completely). Whisk the sauce gently until smooth.
Refrigerate leftovers. I like to keep mine in a glass syrup dispenser. To reheat, microwave for 20 seconds at a time. Stir. Repeat if necessary. You can also place the container in very hot water, wait & stir.