Coat a 9×13 dish generously with cooking spray and set aside. Combine the butter, sugars, corn syrup, evaporated milk and heavy whipping cream in a large saucepan. Cook over medium heat, stirring constantly, until candy thermometer reads 243 degrees F.
Immediately remove pan from heat and stir in the vanilla extract. Pour the caramel into the prepared pan and allow mixture to cool completely. Cut into small squares and wrap in wax paper.
Notes
A high-quality candy thermometer is a necessity for this recipe.
Prepare yourself for nearly an hour of constant stirring. Have someone on standby if you need a break. TRUST ME when I say that the stirring is 100% worthwhile.