A sundae is only as good as its ice cream, and Double Rainbow's ice cream is the bomb. For 27 years now, the San Francisco-based company has been cranking out all-natural, high-butterfat, densely delicious scoops of joy in several dozen flavors, all of them, incidentally, kosher. Pralines 'n' Cream, for example, makes a great foundation for a hot fudge sundae. A huge goblet is filled to overflowing with buttery, pecan-studded ice cream and thick, gooey fudge just warm enough to soften the chill. Whipped cream adds a contrastingly light touch, while a big helping of chopped walnuts and a neon-red cherry provide crunch and bite: It's a simple classic. Double Rainbow's products can be found in over 200 restaurants and ice cream parlors around the globe, but since the company decided to eliminate licensing fees and restrictions a few years ago the locations have assumed a more unique and neighborly ambience. We like the Powell Street outlet, located on a particularly vertical slope of Nob Hill, where you can sit at a little marble-topped table and look out at the cable cars and the Union Square hustle-bustle while you embrace the myriad pleasures of cream, cocoa, nut, and maraschino.