The idea here is that you give each player the same food item and the person who is able to cut it most accurately in half is the winner. Use foods you can then eat, either right at that moment or even for dinner (free prep chef). Each player will attempt to cut the object and eveness of halves will be determined by weighing with a kitchen scale.

Scoring is, as always, completely arbitrary, you can award only the winner or award points on a sliding scale from best to worst. Decide how you wish based on the number of players.

Easiness of this one has a lot to do with the foods you choose, round foods tend to be fairly simple so get a range of shapes. You can even do just water and provide too different vessels (e.g., wine glass and frying pan) to make it harder (tare is your friend). 

If you are going to do this one with kids you will want to adjust for safety reason, you can use soft foods and an alternate utensil (e.g., butter knife, spatula), or use liquids as suggested above.