They're calling the promotion the "Starbucks Via Latte Taste Challenge," and as a further incentive, will also offer $1 off any handcrafted beverage for customers who take part in it.
The new Via Lattes are made with dairy powder, a blend of instant and microground arabica coffee, and nautral flavors. In case you're wondering what dairy powder is, it's also known as powdered milk. The instant mix comes in individual packets and in two flavors: Vanilla and Mocha.
Here's a video detailing the event:
