After you try them, there is no coming back. This concentration of flavours and rich texture is simply irresistible both in dry and sweet wines.
Apassimento is an ancient method of vinification. Harvested grapes are laid on a straw mates to dry on the sunshine. During this process, that can last several months, water from the grape evaporates. This results in 40-70% reduction of grape weight, lowering the quantity of wine that can be produced from it significantly.
Vine made from this grapes (technically raisins) have less tannins, are richer in aromas, higher alcohol content and tend to have more toffee, nutty, brown sugar and fig taste. This way, the Vin Santo, Recioto, Amarone and some Malaga wines are made. Wines produced by this method can be both sweet (by interrupting the fermentation) or dry (by fermenting all the sugar content till the end).
Raisins, that are made by apassimento method, take very long time to ferment, typically about 35-50 days. By drying grapes thus reducing the amount of grape juice, that can be extracted and fermented, this method typically leads to smaller production and higher price tag that follows it in exchange of very concentrated aromas and flavours. Modern version of this method uses special rooms, with artificial heating to assure faster grape drying.
Apassimento method is autochthonous for Itally and there You can find the most wines made with this method.