I use a box to start with. Personally I prefer one that is whole wheat and free of anything artificial. Then I grate up some cheddar cheese and asiago cheese. I cook the mac and cheese according to the box and mix it up. I saute up some onions and add it in with a little asiago cheese. Then I grease a 9x11 pan and put the mac and cheese in it. I add a little milk so it doesn't dry out in the oven. Top it off with the cheddar cheese and put in the oven for about 10 minutes. Then crank up the heat and broil it until it is bubbling and starting to get some brown on the top.