This summer, 24-year-old Ben Van Leeuwen started making his own organic ice cream and selling it out of a refurbished postal truck in Soho. Leeuwen has since parked another truck on the Upper West Side, with plans for a third in Brooklyn. His high-end flavors, like giandujia with Michel Cluizel chocolate and Piedmont hazelnuts, will be sold in Whole Foods and Murray’s Cheese come September. Watch the video to see exactly how to make an artisanal sundae. —Alexandra Vallis

Van Leeuwen Artisan Ice Cream, Greene St. at Prince St., 1 p.m.–8 p.m.; University Pl. at 11th St., 8 p.m.–11 p.m.; Broadway at 75th St., 1:30 p.m.–11 p.m..