Prepare a 9x9-inch or 11x7-inch baking dish -- butter the dish generously, or line it with parchment paper and spray the paper lightly with cooking spray.

In a 4 quart pot (no smaller) over medium heat, bring the butter, corn sryup, sugar, and 1 cup of heavy cream to a boil. Stir continuously, scraping the bottom of the pan with a wooden spoon or heat resistant spatula.

Once the caramel comes to a boil, heat the remaining cup of cream in a LARGE bowl or glass measuring cup in the microwave for 1 1/2 to 2 minutes until hot/boiling. (Will rise as it boils, keep an eye on it so it doesn't spill over.)

SLOWLY add the hot cream to the pot of caramel while stirring continuously. Never allow the caramel to stop boiling or it will become grainy/crystalized. 

Keep stirring the caramel until it reduces by about half and starts to thicken. (About 25 minutes.)

*TEST the caramel once it reaches 225-230 degrees Fahrenheit, by spooning some of the caramel into a small bowl of very cold water. Let it sit for a few seconds. Then pull it out. If it can hold the shape of a ball, then it’s done. Keep in mind, the caramels will firm up a little bit more than the cold water test suggests, so stop when it’s slightly under where you like it.

Remove from heat and stir in the vanilla. It will bubble up so be careful. 

Pour the caramel mixture into the prepared dish. (If some caramel sticks to the sides, leave it. Do not scrape it out. It will be more firm and result in two different consistencies.) 

Let the caramels cool a minimum of 3 hours before cutting. Cut wax paper strips that are 5 to 6-inches long. Then cut each strip into thirds that are about 4-inches wide. 

Cut caramels into squares (8 rows by 8 columns for 64 pieces.) Place a caramel in the center of a wax paper strip. Roll up and twist the ends. Repeat with all caramels.