Prepare the espresso. We're using a Moka pot, but if you're using a different method, prepare your espresso as usual. Fill the bottom compartment with water and add coffee grounds to the filter basket. Screw the top compartment on and place the Moka pot on the stove. Use medium heat to avoid scorching your coffee.
Heat the milk using a milk steamer, stovetop, or microwave. You don't need to froth the milk; it just needs to be hot. Make sure not to boil the milk.
Pull or pour your espresso shots into your coffee mug. Add the hot milk and stir well. You'll want a ratio of about 2/3 milk and 1/3 espresso.
This step is optional, but it's a fun addition! This sugary foam, called espuma, is traditional in Cuban café con leche but is less common in other countries. Pour 2 tablespoons of sugar into a small bowl or creamer. Add an equal amount of espresso and whisk vigorously. You want the sugar to dissolve and the mixture to form a light brown froth. Pour this mixture on top of your café con leche and enjoy your tasty treat!