A café au lait is coffee with hot milk, and that heat is the rule: cold milk in coffee makes a white coffee. What separates it from a latte is the base. A latte is built on espresso extracted at nine bars of pressure in 25 to 30 seconds, while a café au lait uses strong brewed coffee from a drip machine or French press, giving a softer blend. Starbucks sells its version as the Caffè Misto, a fixed one-to-one ratio of French press coffee and frothed milk, standardizing a drink that French servers once poured from two pitchers until the customer said stop. In France it is a breakfast drink served in a wide handless bowl, shaped for dunking croissants, brioche, and baguette.

New Orleans made it something else. At Café du Monde and the Morning Call Coffee Stand, the coffee is laced with roasted chicory root and paired with scalded milk, heated on the stove to around 180 degrees Fahrenheit with no aeration, so its sugars mildly caramelize into a denser, sweeter milk that tames chicory’s woody bitterness alongside powdered sugar beignets. The chicory comes from war. The Union’s 1861 Anaconda Plan blockade choked the port of New Orleans and made coffee scarce, and locals stretched it with chicory, a trick the French had learned during Napoleon’s continental system and Acadian descendants carried to Louisiana.

• Steamed milk is aerated into microfoam, while scalded milk takes on no air at all.
• Chicory belongs to the dandelion family, and its roasted taproot contains no caffeine.
• Chicory is rich in inulin, which brews into a thick, dark, viscous liquid.
• Other desperate populations have stretched coffee with acorns, barley, and even dried carrots.
• Outside of bakeries recreating the French ritual, a café au lait is rarely served in a bowl in the United States.