Mascarpone cheese is an Italian cheese made from milk which has been amended with cream, so that it has a very high butterfat content. The resulting cheese is very rich, creamy, and spreadable; the precise texture varies from very soft, like crème fraîche, to more stiff, like butter, depending on how it is handled during the cheesemaking process. This cheese is native to the Lombardy region of Italy, where it is used in both desserts and savory foods.
Many markets carry mascarpone cheese, typically in small tubs in the refrigerated section. It is also possible to make this cheese at home. Whether you buy or make mascarpone, be aware that the cheese has a very short shelf life; it should ideally be used within a few days, or it can go bad.
Food historians believe that some version of mascarpone cheese has been made in Lombardy since around the 16th century. Most famously, the cheese is used in tirimisu, a layered dish with mascarpone cheese, ladyfingers, espresso, brandy, and chocolate. It also appears in zabaglione, a rich Italian custard. Mascarpone can also be used to make frostings and to thicken puddings and creams for desserts, and it is popular as a standalone dessert, served with fresh fruit and sometimes a light syrup.
If you want to make mascarpone at home, you will need a quart of minimally processed cream and a tablespoon of vinegar or lemon juice. You also need cheesecloth, a strainer, a double boiler, and a reliable thermometer. If you do not have a double boiler, you can make one by positioning a metal or heat-proof glass bowl over a saucepan filled with water.
Start by pouring the cream into your double boiler and heating it slowly. When the cream reaches a temperature of 190 degrees Fahrenheit (88 degrees Celsius), add the tablespoon of vinegar or lemon juice and stir. Curds will start to form immediately in the cream as it reacts to the acid. Once curds form, cover the pan, remove it from the heat, and allow it to stand for 10 minutes before lining a strainer with the cheesecloth and pouring the curdled cream through it.
After you have strained the cream, the cheesecloth will hold a cluster of curds. Allow the curds to cool while draining until they have reached room temperature, and then cover the strainer, place it over a shallow bowl or plate, and refrigerate it for 24 hours. This will set the cheese while it drains. Once this step is finished, the mascarpone cheese is ready to use.