I enjoy Starbucks' iced brown-sugar oak-milk shaken espresso on warm days, so I was looking forward to seeing how oat milk translates into a hot drink. Unfortunately, I was a little underwhelmed.

Starbucks has ... cold foams to milks and milk alternatives. In recent years, one milk alternative in particular has been gaining steam (and froth). Oat milk, a creamy drink made using oats ...