Ganache is traditionally a simple combination of chocolate and dairy cream. Depending on how much cream you use, it works well as a filling for pastry or chocolate truffles, as well as a sauce, icing or glaze. If you don't have access to cream or would prefer a lower-fat alternative, you can substitute condensed milk. This substitution can slightly change the flavor and texture of the finished ganache, but the differences are minor.
Sweetened Condensed Milk
Made from sugar and milk with a reduced water content, this thickened product provides less fat than cream, but it is much sweeter. If you substitute sweetened condensed milk for cream, use unsweetened or bittersweet chocolate, and reduce or eliminate any sugar in your recipe. For thick ganache, use a ratio of about 14 ounces of condensed milk to each 18 ounces of chocolate. For pourable or spreadable ganache, add less chocolate. Sweetened condensed milk can add a mild caramel flavor to your ganache.
Also referred to as condensed or unsweetened condensed milk, this canned dairy product contains little to no sugar. Unlike sweetened condensed milk, it has about the same consistency as cream. According to Gourmet Sleuth, you can substitute it directly for cream in most ganache recipes. This type of condensed milk has much less fat than cream and will produce a ganache with less richness.
Dairy-free Condensed Milk
You can still make ganache if you are vegan or cannot consume milk. For a product with the same richness as cream, use 6 ounces of coconut milk for every 16 ounces of chocolate. You can also make vegan condensed milk as a dairy-free cream substitute with less fat. Combine two parts full-fat soy milk with one part sugar in a saucepan. Bring the mixture to a boil to dissolve the sugar. Simmer for 40 to 60 minutes or until the condensed milk thickens and reduces to one-third the original volume. Cool for 15 minutes and use the same way you would conventional sweetened condensed milk.
Traditional ganache has a very short shelf life. Most recipes keep for only two to three days. According to Pastry Star, using condensed milk in ganache extends it shelf life significantly. Commercial products of this kind last for up to six months before opening. The homemade version has a shelf life closer to that of condensed milk, or between one to three weeks if stored in the refrigerator.