Add the ¾ cup cream and 2 Tbsp butter to a microwave safe measuring cup. Microwave 30-45 seconds or until butter is melted, and set aside.
In a medium pot, add 1 cup sugar and shake to level the grains. Add ⅓ cup water to moisten the sugar.
Turn the heat to medium and cook until the sugar dissolves and turns clear, a few minutes.
Turn up the heat to medium high, and cook until the sugar mixture reaches 340°F. If you don't have a candy thermometer, it should take about 10 minutes and turn an amber color. Make sure not to overcook it 350° or above, and it will start to burn.
Turn off the heat and add the heavy cream and butter mixture. Adding the fat will cause a lot of steam, so be careful. Add a little and stir using the candy thermometer or a spatula. Add the remaining cream mixture. Stir with a spatula until the bubbling ceases, approximately a minute.
Turn the heat back to medium high and cook until the temperature reaches 220°F. If no candy thermometer, cook for about 2-3 minutes or until it reaches a nice caramel color. It will still be runny and will thicken as it cools.
Add 1 tsp vanilla and ½ tsp salt, as desired. Stir until smooth, and allow to cool. Transfer to a jar or container and refrigerate.