Phyllo dough, which means "leaf" in Greek, originated in Turkey during the Ottoman dynasty. Unlike other pastry doughs that contain butter, phyllo is a lean dough, made with flour and water. The dough is rolled into paper-thin sheets, which are brushed with butter and layered with sweet or savory fillings before baking. Phyllo is available fresh in Middle Eastern markets or specialty grocery stores, but it's most commonly sold frozen. It must be thawed in the refrigerator overnight before you use it, but the leftovers, including filled pastries, can be refrozen.

To freeze unbaked pastries that contain filling, place the pastries on a greased baking sheet or a baking sheet covered with parchment paper. Space the pastries so that they do not touch and freeze them for an hour or two, or until they're firm. Transfer the frozen pastries to plastic freezer-safe containers or plastic freezer bags. Seal the containers tightly and label them with the date. Store frozen filled pastries for up to one month. To bake them, preheat the oven and remove the pastries from the freezer. Do not thaw them ahead of time, which will make them soggy. Bake the pastries at the oven temperature indicated by the original recipe, but increase the baking time by 20 minutes.

You can also bake pastries and freeze them until you need them. For this approach, bake the pastries and allow them to cool completely. Stack them in dated, freezer-safe containers, placing a sheet of wax paper between layers of pastries, and then tightly seal the containers. Freeze the prebaked pastries for up to one month. To use them, thaw the pastries overnight in the refrigerator or at room temperature. Pop them in an oven preheated to 375 degrees Fahrenheit for 15 to 20 minutes to warm them and restore freshness. Baked and frozen pastries tend to lose freshness quickly. Thaw only as many as you can use in one day for the best flavor.

When freezing phyllo with filling, consider how well the ingredients in the filling freeze. Traditional sweet pastries that contain nuts, sugar and dried fruit freeze well, but dairy products, such as mascarpone and ricotta, tend to separate when frozen, and vegetables may darken or become soggy.