Spread cheddar cheese thinly across a microwave safe plate (if it is sharp cheddar, then use a bit of oil, very lightly. Regular cheddar has enough fat to not need oil.) Microwave in 20-30 second doses until the cheese becomes crisp but not burnt. You can shatter it with a tap of a knife but it still has oil and moisture. Only cook as much as you will use for 2-3 days and keep it in the fridge in a bag or wax paper wrap during that time.