Put 4 cups of water, 85g of piloncillo, and ½ stick of Mexican cinnamon in a medium saucepan. Simmer over low heat until the piloncillo dissolves, about 7 minutes.
Bring to a boil, add 4 tablespoons of ground dark-roast coffee, turn off the heat, and stir.
Cover, steep for 5 minutes, and pour through a strainer into cups.
