Step 2:
Pour ⅔ cup nonfat or 2 percent milk into a jar with a lid. (Whole milk is richer but foams less, because of its lower protein content.)
Step 3:
Shake the jar vigorously for a minute until bubbly. Uncover and microwave for 30 seconds until froth rises to the top of the jar. (Heating briefly helps stabilize the foam.)
Step 4:
Pour the coffee into 2 mugs, then spoon the frothed milk over the coffee. For the full effect, drag a toothpick through the foam to create swirls.
