Fudge is made of sugar syrups and requires the use of a candy thermometer. Before making the candy, check your candy thermometer for accuracy by placing it in water and bringing the water to a boil. The thermometer should register 212 degrees F (100 degrees C). If the reading is higher or lower, take the difference into account when testing the temperature of a syrup.
To prevent sugary fudge, use a heavy saucepan with straight sides. Stir while mixture heats so candy will not stick and burn. For creamy fudge, remove sugar crystals from pan above the boiling level. To do this, wipe sides of pan with wet pastry brush OR use part of butter in the recipe to grease pan or when candy boils, cover pan for 1 minute to allow steam to wash down the crystals.