Cooking traditional meals using a solar cooker is often challenging because it may require maintaining temperatures of 63 to 180°C for extended periods. A popular Mesoamerican/Mexican dish, “tamale,” is a vapor-cooked corn dough meal/flour wrapped inside corn husk, which may be prepared in a solar cooker. However, its nutritionally rich variety, “elote tamal” prepared from ground fresh corn kernels of tender corncobs with added sugar, fresh milk, and butter, becomes unpalatable under such solar cooking. The initial slow rise in temperature leads to the fermentation of the dough-milk mix and degrades the product. We show that an auxiliary electric heater boosting the temperature at the initial period in an electric-solar hybrid cooker can overcome this limitation. Furthermore, we found significant differences in the total sugar and titratable acidity in the slow-cooked elote tamal. These differences are associated with the incipient fermentation introduced in the milk-containing dough mix during the slow heating stage in traditional solar cooking. We analyzed and compared the protein, fat, moisture content, ash, total sugars, total fibers, titratable acidity, and color of elote tamales prepared under four different cooking conditions. Milk-based tamales under solar cooking require an additional thermal booster at the initial stage to avoid fermentation and eventual loss of quality of the cooked dish. This research is also relevant to the solar cooking of other milk-based meals.