Sometimes it takes a scientist to make a perfect cake.Ehab Sadeek, a chemist by training and a baker out of passion, kept hearing from friends and customers that they were searching for gluten-free baked goods that were not only healthy, but tasty too.The owner of Winchester’s Bagel Land and the former Roast Coffee, he began tinkering with the treats baked in his Somerville commissary.Gluten, the glue that holds baked goods together, is a tricky item to do without.