Dulce de Leche

Sure, you can buy dulce de leche. But then you miss out on that magic that happens when you make it yourself. I'd compare it to the time I wanted to make butter and spent half the afternoon shaking a jar of cream and all I had to show for it was frothy cream. I went ahead and kept shaking it anyway and ended up with, not a minute later, a lump of butter sloshing around in a jar of buttermilk. I couldn't stop grinning about it for the rest of the day. The same fairy dust that requires nothing more than agitating a jar of cream to get butter turns a can of sweetened condensed milk into rich, caramely dulce de leche. Only better. You don't have to shake it for four hours.

This method comes from the Chilean grandmother of a recipe tester for The Essence of Chocolate, a cookbook from chocolate experts John Scharffenberger and Robert Steinberg.
Remove the label from the can. Place the can on its side in a medium saucepan and cover completely with water. Bring the water just to a boil. Keep at a low boil, adding more water as necessary to keep the can covered with at least an inch of water, turning the can from time to time, for four hours. Take care to keep the can covered with water as there's a very slim chance the can could explode if the water boils away. I usually have trouble maintaining a low boil so it ends up being very thick after four hours. A vigorous boil takes only two to three hours.
Carefully remove the can from the water. The dulce de leche can be cooled in the can and stored at room temperature or used right away. If opening the can while it is still warm, open it slowly, because the dulce de leche may spurt slightly.