Granny's Ham And Potato Gratin For A Crowd

• 2 of garlic (cloves)
• 2 qts ham (cooked)
• 4,500 ml boiling potatoes
• 1,900 gr garlic
• 1,500 ml milk (hot)
• 500 gr coarsely cheese (grated)
• 140 gr butter
• 130 gr all purpose flour
• 60 ml dijon-type prepared mustard
• 1 gr thyme