Grilled Orange Egg Custard Cup

1/2 orange or grapefruit, with pulp removed
1 large egg
2 tablespoons milk
Granulated sugar to taste
Cinnamon to taste

Crack egg into a bowl with the milk, sugar and cinnamon; gently whisk with a fork, but don't over-mix.

Place egg mixture in the orange cup. Place over a grilling stand over embers (not the fire). Let cook until egg looks cooked, but not hard.