I tried Martha Stewart's and Ina Garten's baked mac and cheese recipes. The best added an unexpected ingredient.

Martha Stewart and Ina Garten both have recipes for baked mac and cheese, so I put them to the test. Erin McDowell/Business Insider Summer cookouts are the perfect opportunity to break out a bubbling pan of baked mac and cheese. Celebrity chefs Martha Stewart and Ina Garten both have recipes for baked mac and cheese. Stewart's recipe uses four kinds of cheese and yellow onion, while Garten's calls for tomato. Summer cookouts are just around the corner, and few side dishes are as crowd-pleas...