To make a homemade version of Kahlua, a coffee liqueur, infuse light rum with espresso, simple syrup and vanilla beans for three days before removing the beans and bottling the liqueur. For alternatives, try vodka instead of rum or instant coffee in place of espresso.
Prepare the coffee and the simple syrup first. To make a cold-brewed espresso, combine 1/4 cup of fine espresso grounds with 1 1/4 cup of water in a glass jar. Seal and shake the jar, and place in a refrigerator overnight or at least 12 hours. Using a coffee filter, strain the mixture to remove the grounds. To make a simple syrup, boil 1 cup each of sugar and water, and remove the mixture from the heat to allow the syrup to cool to room temperature.
In a large jar, combine the espresso, simple syrup and 1 1/2 cups of light rum with a vanilla bean. Let the alcohol infuse for three days in a cool, dark location. Once the rum is infused, remove the vanilla bean, and bottle the coffee liqueur for future use.
Other homemade variations utilize vodka instead of rum or a combination of dark rum and either light rum or vodka. For additional flavor, try adding some cocoa nibs, a cinnamon stick or an orange peel during the infusion process.