(MONEY Magazine) – When you think of ice cream, premium-priced brands like Haagen-Dazs and Frusen Gladje probably pop to mind. But if you want to invest in ice cream, think downscale, says Glenn Johnson, a restaurant analyst at Piper Jaffray & Hopwood in Minneapolis. One of the most consistently profitable franchisors is International Dairy Queen (OTC, $24.25). From its ubiquitous roadside stands -- 4,351 of them throughout the U.S. -- the 46-year-old Minneapolis-based company dominates the frozen dairy snacks trade, ringing up an estimated $180 million sales in 1986. The ice cream may be soft, but the earnings have been solid, rising by an average of 30% a year for the past five years. While such growth can't last, Johnson thinks 18% a year is sustainable through 1991. ''Dairy Queen will achieve fast growth because it is continuing to test new entries on its menu, such as soup, salad and shish kebab,'' he says. With only about 7 million shares trading, the company is not widely followed by analysts. At 16 times Johnson's estimate of $1.50 per share earnings, Dairy Queen is trading near the bottom of its 52-week P/E range of 14 to 28. Because of its small size and fast growth rate, Johnson recommends the company only for aggressive investors. He would consider selling if the P/E rose above 20.