Try this Condensed Milk Mocha Cold Coffee recipe
Standard iced coffee relies on simple syrup or granulated sugar dissolved directly into warm liquid. This preparation diverges by utilizing sweetened condensed milk, which introduces concentrated dairy solids alongside sucrose. Combining the hot coffee at 200 degrees Fahrenheit with cocoa powder requires vigorous whisking to hydrate the starches and fats in the cocoa solids before any cold ingredients enter the vessel. Whisking the cocoa into the hot coffee prevents the formation of unhydrated lumps that typically float on the surface of cold beverages.
Pouring hot coffee directly over ice causes rapid thermal shock, which melts the ice unevenly and dilutes the beverage beyond recognition. Chill the combined mixture in the refrigerator for at least two hours until the internal temperature drops below 40 degrees Fahrenheit before serving over fresh ice cubes. Whole milk provides 3.25 percent milkfat, which coats the palate and balances the bitterness of the brewed coffee. If substituting half-and-half, use a 1:2 ratio with water to maintain the intended viscosity.
Condensed milk contains roughly 40 to 45 percent sugar by weight, meaning minor adjustments to the quarter-cup measurement dramatically alter the sweetness profile. Whisk the condensed milk thoroughly into the hot liquid to ensure complete dissolution, as dense milk sugars tend to settle at the base of the container if left undisturbed. Store the mixture in an airtight glass pitcher for up to 48 hours in the refrigerator. Stir the contents before serving, as natural separation may occur during extended chilling.