Caramel Apples

Last night I found myself craving a caramel apple but there was a problem - no caramels to unwrap and melt and no cream or evaporated milk for making homemade caramel. I did have a can of sweetened condensed milk, however, and so I ran downstairs to pick the brain of the Internet.
I found this recipe and tried it. It turned out quite well! The flavor is more robust than most caramel recipes I've tried and the consistency is perfect for covering an apple. Here it is:

Caramel Apples

1 cup butter
2 cups brown sugar, packed
1 cup light corn syrup
1 can sweetened condensed milk
2 tsp. vanilla extract
8-10 medium-sized apples, washed, dried, with sticks inserted (I was fresh out of popsicle sticks so I used chopsticks, as you can see from the picture!)

Over medium-high heat, stir together the butter, sugar, corn syrup, and condensed milk in a heavy sauce pan. Bring to a boil. Reduce heat and continue cooking about 30-40 minutes, stirring occasionally until the caramel darkens and thickens. It should reach the "firm ball" stage (240-250 degrees on a candy thermometer).

Remove from heat and stir in the vanilla extract. Dip apples into hot caramel.
Hint: In order to get as thick a caramel coating as possible, dip at an angle and rotate the apple in the caramel. Allow excess caramel to drip off. Then turn the apple right-side-up for a few seconds and let the caramel set up. Then you won't end up with a big puddle of caramel at the bottom of the apple.

Place on a buttered cookie sheet, wax paper, or foil until cool.