Place the following drinks in order from the least milk to the most, relative to espresso: cappuccino, double espresso, latte, macchiato.

The correct ordering of the drinks from least milk to most relative to espresso reflects the composition and preparation methods of each beverage.

A double espresso consists solely of espresso without any milk, making it the least milky option. Following that, a macchiato typically features a shot of espresso "stained" with a small amount of milk foam, so it contains a little more milk than a double espresso but still remains quite concentrated.

Next is the cappuccino, which traditionally comprises equal parts espresso, steamed milk, and milk foam. This means it has a substantial amount of milk relative to the espresso, increasing its milky character compared to the previous drinks.

Lastly, the latte contains the most milk of these options. A latte is made with a significant amount of steamed milk and a smaller amount of foam on top compared to a cappuccino, balancing the espresso with creaminess.

This ordering clearly reflects the milk content in relation to the espresso shots, affirming that the double espresso has no milk, the macchiato has a little, the cappuccino has more, and the latte has the most.