Note: If possible, recruit an extra person or two to help cut and wrap the caramels. It can be done on your own with no real problem, but extra hands make the job easier. If you are doing the wrapping and cutting on your own, I would advise doing it in stages: cut all the wax paper squares, then cut the caramel into individual pieces, then wrap them according to directions. Rinse your hands occasionally with hot water, then towel-dry, to remove any residual stickiness.
Butter an 8x8 inch pan. Line the pan with foil, folding any excess over the outside edges; set aside.
Mix the butter, brown sugar and corn syrup in a microwave-safe glass bowl or measuring cup. I use my 4 cup Pyrex measuring cup or my 8 cup Pampered Chef measuring/mixing bowl, both of which have a handle.
Microwave on high for two minutes.
Stir mixture and return to microwave for two minutes longer.
Add 2/3 cup sweetened condensed milk and stir well.
Microwave three and a half more minutes.
Remove from microwave and stir in 1/2 tsp vanilla.
Pour into prepared pan, scraping any residual caramel from the sides of the bowl. Be careful not to touch the caramel, as getting a sugar burn would put a real damper on your day.
Set aside and let cool to room temperature.
While the caramels are cooling, cut the wax paper squares; set aside. Note that the number of servings is dependent on how large/small you cut the caramels.
When the caramel is cooled, remove foil liner from the pan via the foil wings folded over the top of the pan.
Cut into approximately 1 inch squares with a well-buttered knife or dough scraper, being careful not to cut through the foil.
Butter your hands well, then place one caramel in the middle of a wax paper square. Roll it into a cylinder, then twist the ends.