Add 1/4 cup cold milk or cream to a jar, cup, or frother
Add 1 to 2 tablespoons sweetener if desired
Add 1/2 teaspoon vanilla extract if desired
Froth with a handheld frother for 20 to 30 seconds
Or shake vigorously in a sealed jar for 30 to 60 seconds
Or blend briefly in a blender until foamy
Spoon the foam over cold coffee or iced drinks
Serve immediately