What the Fluff? A Tribute to Union Square Innovation is a madcap festival honoring the invention of Marshmallow Fluff, returning for its 19th year to the delight of Fluff enthusiasts from Greater Boston and beyond.

Blue River and Ciao have teamed up to create The Original Fluff Cannoli! Ciao, known for the best pizza in Boston and led by Chef Marvin Posada, collaborated with award-winning Blue River Terps, William Ford and Tony Verzura, to craft this unique treat. They will offer Chocolate Fluff and Blueberry Lemon Fluff Cannolis, featuring non-medicated Blue River’s Vanilla Bean and Blueberry Lemon Real Fruit Syrup combined with Ciao’s homemade Marshmallow Ricotta Fluff filling. Cannolis will be sold for $2 each or 2 for $3 (while supplies last) at the booth from 2pm to 6pm, with free merchandise giveaways.

It celebrates Somerville’s proud tradition of innovation with live music, fluffalicious feasts, sticky games, zany happenings, and much more on Saturday, September 21 from 2-6pm in Union Square