Gus “Isgro” Sarno can go on forever about cannoli. The fried-and-filled pastry wrap is an obsession he inherited from maternal grandfather Mario Isgro, who founded this Italian Market business 101 years ago. Sarno will tell you each shell must be 1.5 millimeters thick, and that a special blend of homemade red and sweet white wines makes it blister. He can quote the exact moisture content of the cinnamon-kissed ricotta-chocolate chip filling (63 to 64 percent). Still, that doesn’t mean the shop neglects its other wares. The second-best-seller is cassata, Italian rum cake enrobed in pebbled almond candy. And during the winter holidays, a close third is precious, pistachio-chocked, stick-to-your-molars torrone, sold by the rugged brick.