Line the dish/pan you'll be pouring the molten caramel mixture into with parchment paper. That way you don't need to worry about caramel sticking everywhere. I use an 8x6 glass baking dish.

Add the white sugar, brown sugar, corn syrup, evaporated milk, cream, and butter to a medium-sized pot.

On medium-low heat, warm the mixture and stir frequently until it reaches 250F (use a candy thermometer). This should take around 40-50 minutes or so. You'll notice the mixture thickening significantly when it's almost ready. Stir more frequently as it approaches 250F - as it gets closer the temperature rises fast. If you want softer, chewier caramels, you'll want to stop at the "soft ball" stage, which is 235F-240F.

Stir in vanilla and mix it thoroughly.

Transfer it to the pan/glass dish lined with parchment paper.

Let cool for at least an hour.

Cut into squares and wrap in wax paper.