In a heavy-bottomed saucepan, combine the granulated sugar, heavy cream, light corn syrup, and salt. Stir gently to blend everything evenly. Avoid scraping the sides too much, as that can cause sugar crystals to form.
Place your candy thermometer into the pot, making sure it doesn’t touch the bottom. Cook the mixture over medium heat without stirring. Let it bubble and come to 260°F—this is the hard-ball stage, and hitting this temperature is critical. It should take about 15–20 minutes.
Once it hits the right temperature, immediately remove the pot from heat and pour the hot mixture onto a generously buttered marble slab or heat-resistant surface. Be very careful—this is extremely hot sugar. Let it sit for about 1–2 minutes, just until the candy starts to firm up but is still pliable.
Once the candy is cool enough to handle but still pliable (around 2–3 minutes after pouring), grease your hands thoroughly with butter. You’ll also want to butter your bench scraper or butter knife if you’re using one to help fold the candy.
Use your hands or scraper to lift the edges of the candy and begin folding it over itself. As it starts to hold together, pull the candy into a long rope, then fold it back on itself. Repeat this process—pull, fold, twist—for about 10 to 15 minutes.
As you continue pulling, you’ll notice a dramatic shift: the candy will go from translucent and glossy to opaque, creamy, and pearlescent. That’s your signal that it’s ready!