A sturdy, heavy-bottomed pot is essential to prevent scorching, as thinner pans can cause the sugar to burn along the edges. For best results, lift the walnuts from the pot individually or in small clusters; tipping them all at once may cause them to harden into an inseparable mass. Stir constantly and monitor the color—once the caramel turns golden brown, act quickly to avoid burning. Raw walnuts are ideal, as they toast naturally in the hot caramel. For added flavor, sprinkle cinnamon or other spices into the mixture just before removing from the heat, or finish with a pinch of sea salt while the nuts are cooling on the parchment.