Espresso is a unique brewing method that requires specific proportions of coffee and water to achieve the ideal flavor profile. Generally, a single shot of espresso is made with about 7-9 grams of coffee, yielding approximately 30 milliliters (1 ounce) of liquid. A double shot, on the other hand, typically uses around 14-18 grams of coffee to produce around 60 milliliters (2 ounces) of espresso. Any deviation from these measurements can lead to under-extraction, resulting in a sour taste, or over-extraction, leading to bitterness.