The most simple way to make gravy out of bouillon cubes is 1)Melt the boullion cube in a cup of hot water. 2) Put about 2 tbsp flour into a non-stick fry pan and brown it by heating the pan and continuously moving flour until it gets a little golden brown. 3) Add a little melted butter into the pan and mix it well till it becomes a smooth paste. 4) Add melted bullion cube mixture to your flour paste and stir on low flame until smooth and liquid as gravy should be, but, do not use all the salty bullion melted cube liquid, use some plain water in the pan to get a balanced flavor. You could add some onion powder or fried onions or fried mushrooms to your gravy also sprinkle little bit of pepper.