1/2 cup whipping cream or non-dairy whip, room temperature
2 Tbsp unsalted margarine, room temperature
1 tsp fine salt
1 tsp vanilla extract
1 cup creamy peanut butter, optional
In a medium saucepan, combine the sugar, cream of tartar and water and set over low heat. Whisk constantly until the sugar dissolves completely and the syrup is clear, around 8 minutes. Do not rush this step or the sugar will crystallize.
When the sugar is fully dissolved, attach a candy thermometer to the saucepan and raise the heat to medium-high. Bring the syrup to a boil while continually stirring.
Once the syrup is boiling, stop stirring and let the mixture boil without touching it until 350 degrees F and a medium-dark amber color, around 10-15 minutes.
Remove the pot from the heat and add the whipping cream then the margarine. Be careful because the mixture will sputter and foam at this point.
When the mixture settles down, stir with a silicon spatula until smooth. Return the pot to the stove and boil until the mixture reached 248 degrees F, around 1 minute.
Remove the pan from the heat and add the salt and vanilla. Stir to combine.
If making peanut butter caramel, let the caramel cool for 10 minutes then stir in the peanut butter.