This will take time and patience. You need to be extremely cautious if you have children around this dog.

With time you can desensitize him, and get him to realize that something yummy is coming his way!

Start with trading. Have something yummy - a bit of hot dog, boiled boneless skinless chicken breast, or cheese. Call to get his attention and toss it away from his dish. As he goes to get it, toss another piece of yummy treat IN his dish AND WALK AWAY. You will have to do this over and over before you can move to the next step. At the start, you will see him perhaps charge back to his dish as you toss the second piece in. With time, he is going to wait for you to put the second treat in. When you see him do this - pause even a MOMENT - for the second treat to land in his dish, smile, say "YES!" and still move away. You want to "mark" or reinforce the positive action he does. DO NOT MAKE EYE CONTACT while you are doing this exercise. This may take 3 weeks, especially if you are only feeding him once a day. Patience.

Next step, you will PLACE rather than toss the second piece in his dish; and move the dish slightly. I'm talking fraction of an inch. Everything else stays the same. Tossing the first piece to make him move away (you want to be SAFE), no eye contact, "YES!" the moment he pauses, stops, lets you do what you want to do. If he growls, snaps, go back to the first step for another 4 days or more, then try again. You want to set him up for success. So if you move to a harder level and he reacts, he is not yet ready for that.

Next, you will actually PICK UP the dish to add the second piece. At first, you may be crouched down and only picking it up an inch off the ground. Again, if he is not ready for this, revert to the prior step for a longer time. And everything else stays the same.

The whole process could take several months. Just remember, this will pay off and you will have years of better behavior once you have calmed him. And these few months of training will fade into the background.