These caramel-dipped hazelnuts make a lovely garnish on a plated dessert.
Insert a toothpick into the side of each hazelnut. Place a sheet of parchment on the counter and the Styrofoam on top of it (you can elevate the piece of Styrofoam a bowl or container, so that it sits a few inches above the parchment. Have a metal bowl filled with ice water on hand for to immerse the pot of sugar.
Bring the water, sugar and corn syrup up to a boil over high heat without stirring. Boil the sugar, occasionally brushing the sides of the pot, until the sugar turns a light amber colour, about 5 minutes. Remove the pot from the heat and immerse the bottom of the pot into the ice water to halt the cooking. Gently swirl the sugar until you see that it is thickening and then beginning dipping the hazelnuts, one at a time.
Use the toothpick to hold each hazelnut as you dip it halfway into the sugar. Hold it above the pot for a few seconds to let the sugar drip off, then stick the toothpick into the Styrofoam so that the hazelnut rests about 6 inches (15 cm) above the parchment. As the caramel cools, the thread of caramel that comes down from the hazelnut will set. Repeat with the remaining hazelnuts, until all are dipped. If the sugar becomes too thick or sets up, reheat over low heat, stirring very gently before continuing. Once the hazelnuts are set, remove the toothpicks and store the “spikes” in an airtight container for up to a week.