>>21407402 (OP)>What is their secret?No idea. But there are 100s of cultivars & varieties of mangos and they can be floral and rich in flavors and scent both, kind of like how wines are vastly different. My guess is that they use frozen chunks of ripe mango with their usual vanilla shake. Alphonse is a common commercial variety that even tastes creamy. My neighbor has "champagne" variety that tastes like lychee honey. Ask an employee to show you the bag so you might known which variety. It'll be on the label. Fairchild Tropical Garden in Miami has an annuald festival where you can try them all. They really do taste vastly different.
ChickFilA makes an amazing shake too, adding ripe peaches to their vanilla shake and frosted lemonade recipes this time of year too. They literally just press pulse on the blender.