McDonald's 'mirror of Starbucks' is revolutionizing the chain's business - here's how

In September, McDonald's announced that it had added a new set of espresso-based drinks to the menu: a caramel macchiato, a vanilla cappuccino, and an americano.

The new drinks were controversial among franchisees, who said that the new offerings took too long to make and required unnecessary, expensive equipment.

However, on Tuesday, executives said that the McCafe initiatives had paid off in sales. The fast-food chain reported that sales at stores open in the US for at least one year rose 4.1%, marking the chain's third consecutive quarter of increasing sales.

Coffee is "a $30 million business in the US," McDonald's US President Chris Kempczinski said in a call with investors. And, there are four specific things that McCafe can bring to McDonald's business that other fast-food items can't.

Here's why gourmet McCafe is a key part of McDonald's future: