As of 2015, available K-cup flavors do not include white chocolate mocha. However, Indulgio makes a white chocolate caramel cappuccino K-cup that may be close to the desired flavor. Another option is to brew one K-Cup of white chocolate hot chocolate and one K-cup of strong coffee, and combine them.
Timothy's World Coffee produces a white chocolate hot chocolate K-cup, and Van Houtte makes a white chocolate mint K-Cup. Both of these flavors are available online at the Save a Latte website.
Indulgio's white chocolate caramel cappuccino K-cup can be found on the company's website, as well as on Koffee Outlet's website.