In a large glass mixing bowl combine butter, sugars and corn syrup. Microwave for 5 minutes. With hot pads, remove the bowl from the microwave and stir. Pour in one can of sweetened condensed milk and stir.
Place bowl back in the microwave and cook for another 10-15 minutes stopping the microwave and stirring every 3 minutes. For the last 1-2 minutes, stir the caramel and check temperature every 30 seconds.
Check the consistency of the caramel by dropping a few drops into a bowl of ice water, if the caramel forms and soft ball it is ready. If using a thermometer, it should reach 235º F
Once the caramel is finished, stir in the vanilla and then carefully pour into greased pan and cover with plastic wrap. Place the caramel in a fridge overnight, or in the freezer for one hour, until cool enough to handle.
Remove caramel from the pan and slice into bite sized pieces. These can be wrapped in parchment paper for sharing.
Video
Notes
Nutrition facts are just an estimate
These can be made ahead and wrapped in waxed paper then frozen for up to 3 months.
Remove the caramel from the pan with a spatula or run the pan upside down under hot water to help release the caramel if it is hard to remove.
Use a sharp knife to slice the caramels into smaller pieces
These are good for 1 week if kept in the refrigerator in an air tight container